diff --git a/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py b/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py
index 3681a34f9fc666bfec9f7cfecbde14e9d9e485c8..54de2d0b8107f68ffccf84a9e6ada4c928dd8b12 100644
--- a/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py
+++ b/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py
@@ -496,9 +496,9 @@ class PlottingWidget(QtWidgets.QScrollArea):
         When click mouse on the current plottingWidget, SOHView will loop
             through different plottingWidgets to do the same task for
             interaction:
-            + shift+click: call on_shift_click() to do zooming. This is
-                disregarded in TimePowerSquareWidget because it isn't subjected
-                to be zoomed in.
+            + shift+click:  is disregarded if start in TimePowerSquareWidget
+               * If click on left side of the plot (xdata<xmin): call zoom out
+               * Otherwise: call on_shift_click to do tasks of zoom in
             + ctrl+click or cmd+click in mac: call on_ctrl_cmd_click() to show
                 ruler
 
@@ -556,7 +556,12 @@ class PlottingWidget(QtWidgets.QScrollArea):
                 except AttributeError:
                     pass
             if modifiers == QtCore.Qt.KeyboardModifier.ShiftModifier:
-                w.on_shift_click(xdata)
+                if xdata < w.min_x:
+                    # click on left of plot
+                    w.zoom_marker1_shown = False  # reset zoom in
+                    w.zoom_out()
+                else:
+                    w.on_shift_click(xdata)
             elif modifiers in [QtCore.Qt.KeyboardModifier.ControlModifier,
                                QtCore.Qt.KeyboardModifier.MetaModifier]:
                 w.on_ctrl_cmd_click(xdata)
@@ -617,11 +622,6 @@ class PlottingWidget(QtWidgets.QScrollArea):
 
         :param xdata: float - time value of a channel plot
         """
-        if xdata < self.min_x:
-            # click on left of plot
-            self.zoom_marker1_shown = False     # reset zoom in
-            self.zoom_out()
-            return
         if not self.zoom_marker1_shown:
             self.ruler.set_visible(False)
             self.set_ruler_visibled(self.zoom_marker1, xdata)
diff --git a/sohstationviewer/view/plotting/time_power_square/time_power_squared_widget.py b/sohstationviewer/view/plotting/time_power_square/time_power_squared_widget.py
index 733d5684b52e75c07ed06fd88a639b3516614361..6de150a0e058c1e67eee62c03a7c4738dbae6637 100644
--- a/sohstationviewer/view/plotting/time_power_square/time_power_squared_widget.py
+++ b/sohstationviewer/view/plotting/time_power_square/time_power_squared_widget.py
@@ -579,6 +579,16 @@ class TimePowerSquaredWidget(plotting_widget.PlottingWidget):
             self.set_lim_markers()
             self.zoom_marker1_shown = False
 
+    def zoom_out(self):
+        """
+        Zoom out by setting limit to the previous range when there's at least
+            one zoom-in.
+        """
+        if len(self.zoom_minmax_list) > 1:
+            self.min_x, self.max_x = self.zoom_minmax_list[-2]
+            self.zoom_minmax_list.pop()
+            self.set_lim_markers(is_zoom_in=False)
+
     def set_rulers_invisible(self):
         """
         Clear data for self.rulers to make them disappeared.
@@ -586,12 +596,20 @@ class TimePowerSquaredWidget(plotting_widget.PlottingWidget):
         for rl in self.rulers:
             rl.set_data([], [])
 
-    def set_lim_markers(self):
+    def set_lim_markers(self, is_zoom_in=True):
         """
-        Find x index (which index in five minutes of a day) and
-            y index (which day) of self.min_x and self.min_y, and set data for
-            all markers in self.zoom_marker1s and self.zoom_marker2s.
+        + Append to zoom_minmax_list if called from a zoom_in. First time
+        plotting is considered a zoom_in to create first x range in the list.
+
+        + Find x index (which index in five minutes of a day) and
+        y index (which day) of self.min_x and self.min_y, and set data for
+        all markers in self.zoom_marker1s and self.zoom_marker2s.
+
+        :param is_zoom_in: if set_lim comes from zoom_in task
         """
+        if is_zoom_in:
+            self.zoom_minmax_list.append((self.min_x, self.max_x))
+
         five_minute_idx, day_idx = find_tps_tm_idx(self.min_x,
                                                    self.start_5min_blocks,
                                                    self.start_first_day)