The invention provides a detection method and a detection device of automatic dependent surveillance-broadcast. The detection method of the automatic dependent surveillance-broadcast include the steps of preprocessing, pulse position detection, preamble pulse detection, preamble reference power value calculation, and automatic dependent surveillance-broadcast (ADS-B) signal validation, wherein the preamble pulse detection includes the steps of matching and detecting pulse positions of an input signal by reading a rising edge and a falling edge of standard ADS-B signal preamble and an effective pulse position, and the ADS-B signal validation includes the steps of comparing the calculated preamble referent power value with power of each preamble pulse in the input signal, when comparison results are consistent, the input signal is confirmed as the effective ADS-B. The invention further provides a computing method which ensures effectiveness of the preamble reference power value in compliance with the minimum variance criteria. The detection method and the detection device of the ADS-B have the advantages of being high in detection probability, less in logic resource consumption, and particularly suitable for detecting an ADS-B signal by using a programmable logic device, namely a field programmable gate array (FPGA).