The invention discloses a multifunctional data conversion system based on an airborne collision avoidance system, comprising an atmosphere height conversion unit, a radio height conversion unit, and a flight parameter conversion unit. An aircraft atmosphere data machine and an aircraft radio altimeter are respectively connected with the input ends of the atmosphere height conversion unit and the radio height conversion unit. The flight parameter output end of the airborne collision avoidance system is connected with aircraft flight parameter equipment. The multifunctional data conversion system is easy to implement in engineering, and can complete atmosphere height, radio height and flight parameter signal format conversion between the aircraft equipment and the collision avoidance system according to the requirement of an aircraft platform. An adopted sampling circuit reduces the sampling error of analog data conversion and improves the sampling precision of an analog data conversion system. The function of conversion between RS422 data and ARINC429 data and conversion between high-speed ARINC429 data and low-speed ARINC429 data is added.