According to the features of air-to-air missile with radar seeker and the characteristics of velocity and acceleration in radar echoes, the mathematical model of missile target echo signal was established. The frequency domain masking technique was adopted to mask the peak fields of the radar echo's Fourier transform data. Based on the focus of LFM signals, the signal's detection and parameter estimation of missiles based on FRFT were presented to detect and estimate weak component LFM signals from strong component signals. The algorithm was verified can imply a reliable early warning of missile launching.