The invention discloses a video field synchronizing signal generating circuit which adopts a uniform structure and can realize that a field synchronizing signal is generated when SDTV, HDTV and VESA standard video signals, non-standard video signals and abnormal video signals are input according to different parameters. The circuit can be used for processing the standard video signals, the non-standard video signals and the abnormal video signals; and when the circuit is used for processing the abnormal video signals, the field synchronizing signal can generate an odd-even field blanking signand a frame line sign code through a pixel clock signal freely operating inside, thus the field synchronizing signal can be generated.