The invention discloses an automatic ADS-B double-data-chain switching device based on height. The automatic ADS-B double-data-chain switching device is characterized by comprising a data receiving module, an information extraction module, a format conversion module, a reconfigurable function module and a baseband processing function module, wherein the reconfigurable function module comprises a configuration interface module, a configuration control module and a configuration data storage module; the baseband processing function module comprises a framing and encoding module and a modulation transmitting module. Two ordinary data chains of 1090ES and UAT in air traffic control are adopted, and hardware configuration files of different data chains are highly automatically selected and loaded, dynamic loading and adjustment on working data chains are achieved, and functions of an onboard navigation management monitoring system are relatively complete, so that full-airspace monitoring on an aircraft can be achieved, the monitoring efficiency of the onboard navigation management monitoring system is improved, the flying security can be improved, and the airspace utilization rate can be increased.