The influence of tracking loop time constant and decoupling coefficient on the missile guidance and control system is studied in this paper. The two parameters represent the performance of the digital stabilized platform for the phased array radar seeker. Firstly, a mathematical model of missile guidance and control system using strapdown radar seeker is established by reasonable assumptions. Then, the relationship between the stability of the coupling loop and the two parameters is obtained by using the Routh-Hurwitz criterion. The Ad-joint System Method is used to study the influence of the parameters on miss distance. Theoretical analysis and numerical simulation results show that the performance of the digital stabilization platform will affect the stability of the coupling loop and ultimately affect the miss dis-tance of the missile.