According to the typical scene of automatic landing and the parameters of landing guidance radar,the causes of measurement errors,error types and error magnitude of radar guidance positioning are analyzed in detail.The calculated accuracy of radar positioning is consistent with the performance of the published AN/SPN-42 radar.The architecture of Automatic Carrier Landing System(ACLS) is designed and the simulation of the system based on F/A-18A aircraft is constructed.The disturbance factors of radar guidance error,automatic landing system delay,carrier air wake,deck motion and airborne sensor noise are introduced.The touchdown point standard errors are calculated by numerical experiment to illustrated the landing performance.and the influence of disturbance factors on landing results is quantitatively described by regression analysis.The results show that the amplitude of deck motion has the most significant effect on the standard deviation of touchdown point.