A multifunctional debugging interface conversion device comprises a parallel interface conversion module, an RS232 conversion module, an RS485 conversion module, a data control module, a mode selection module, a cable clamping machine and a USB (universal serial bus) connector, wherein the cable clamping machine comprises a parallel interface terminal and a serial interface terminal, the mode selection module comprises a dial switch and an encoder, the data control module comprises a control chip and a USBHUB chip, which are connected with each other, the USB connector is connected with the USBHUB chip, a conversion chip of the parallel interface conversion module, a conversion chip of the RS232 conversion module, a conversion chip of the RS485 conversion module and the encoder are respectively connected with the control chip, and the control chip selectively switches on corresponding interface modes according to dial codes of the dial switch. The multifunctional debugging interface conversion device is small and exquisite in appearance, and convenient to bring and use, can achieve conversion between a serial interface mode and a parallel interface mode through the dial switch, meets demands of different debugging interfaces, and can not cause the problems that a device can not be debugged due to the fact that a wrong debugging line is carried when the device is debugged and a worker needs to carry two or three debugging lines for debugging the device.