@AlbertRicky said in Image can't Show in Page2:
so what should I use to make two pages
Change the secondWindow type to QWidget (using QMainWindow there is weird) and make it a page of QStackedWidget.
You can design that widget with your QtDesigner and setup the layout with the label that should hold your image later.
Assign your result image with your detections to the label, when you have processed the source image and flip the pages with your buttons.
This can also be done in-place. Then you dont need a QStackedWidget. If you don't need to switch back and forth multiple times, but swtich one time to show the result, you could also "replace" the image on your current label, when clicking the button. But I dont know, what else you what to do on that second page widget.