The invention discloses a bidirectional satellite navigation and communication positioning method and system, relating to a satellite technology. The system is provided with an outcoming and incoming positioning link and a communication link, comprises satellite ground stations (a master station and an auxiliary station), a synchronous communication satellite and various user terminals, is a highly-integrated navigation positioning and communication integrated bidirectional information system, has various functions, such as bidirectional pseudorange measurement, positioning, velocity measurement, posture measurement, direction finding, time service, help calling, monitoring, surveying, communication, search and rescue, service, and the like and has the characteristics of high precision (relative positioning precision: millimeter level (1Sigma); measuring frequency: 50Hz; velocity measurement precision: 0.01mm/s; bidirectional time service precision: superior to 0.1ns; and communication information transmission rate: 50bps-2400bps), less investment, short construction period, good completeness, high reliability, and the like.