The error sources that influence the precision of atmospheric retrieval parameters obtained by the atmospheric occultation sounding system are studied. Each error which contributed to the total variance of the product was analyzed in detail, such as the Doppler observation error, the antenna phase center changing error, multipath error, the satellite centroid change error, the GNSS satellite clock drift error, satellite attitude variety error and the velocity error of precise orbit determination. The main errors that must be accounted carefully are the Doppler observation error, the multipath error, the antenna phase center changing error and the satellite attitude variety error. Especially if the distance between the satellite centroid and the occultation receiving antenna phase center is larger than 0.5m, or the satellite attitude variety is larger than 0.01(°) ·s-1
, the error will become unacceptable. According to the implementation feasibility, the total error allocation scheme can offer a reference for the system design of atmospheric occultation sounding system.