An interface converting circuit applied between a 3D de-interlace chip and a rear-end image compression chip. The interface converting circuit includes: a reducing FPS circuit, for dividing a first vertical synchronization signal to generate a second vertical synchronization signal, and converting a first horizontal synchronization signal to a second horizontal synchronization signal by masking the first horizontal synchronization signal according to the second vertical synchronization signal; a pixel clock multiplier, for multiplying a first pixel clock signal to generate a second pixel clock signal; and, a data-width converter, for converting an input signal with M bits data width, which is transmitted at a frequency of the first pixel clock signal by the 3D de-interlace chip, to an output signal with M/2 bits data width, which is transmitted at a frequency of the second pixel clock signal.