In view of the fact that the PPP (Precise Point Positioning) is not actually supported by 5G network currently, the message format of SSR (State Space Representation) assisted data transmitted in the LPP(LTE positioning protocol) layer has been studied. After listing the parameters related to the PPP, a LPP message format for transmitting SSR assisted data was designed, and simulation experiment utilized 5G physics broadcast channel was used to investigate availability of message format. The results show that the dual-system dual-frequency precise point positioning accuracy is 0.08 m, 0.15 m and 0.31 m in the N, E and U directions respectively, and accuracy improvement is 40% and 64% in the N and E directions respectively at the expense of the extra information of 1 040 bytes per minute，compared with GPS single system. It is concluded that the message format is available, and the accuracy is improved with the increase of information.