Abstract: Mutual interference between automotive radars may reduce the sensitivity of the sensor, and false alarms may occur sometimes. To solve this problem, this paper proposed an interference suppression method based on particle swarm optimization and adaptive cancellation. This method combines waveform optimization at the transmitter and adaptive filtering at the receiver to further improve the radar's interference suppression capabilities. First, the particle swarm algorithm is used to optimize the waveform parameters to minimize the waveform similarity within the parameter constraints and alleviate the false alarm problem. Then, based on the characteristics that the interference is conjugate correlated in the positive and negative spectrum and the target is only in the positive half of the spectrum, obtain the optimal filter through least mean square iteration to achieve adaptive interference cancellation. The simulation verifies that this method has a good suppression effect for many kinds of interferences.