The invention discloses a simulator of GNSS receivers. The simulator of the GNSS receivers comprises servers, the GNSS receivers and clients, wherein the servers are connected with the GNSS receivers, and are used for obtaining time data and observation data of satellites and ephemeris data and almanac data of the satellites from the GNSS receivers in a real-time mode, and communication is carried out between the servers and the clients through a network. The high-precision simulator of the GNSS receivers can serve thousands of clients at the same time, and provide the observed quantity similar to observed quantity in reality, and operating experience, similar to operating experience on real receivers, on the receivers, the risk of damage does not exist, a user can carry out operation at will, the teaching effect of related courses of an GNSS is greatly improved, a flexible data generation platform is provided for data processors of the GNSS, a large amount of time for data collection can be saved, and efficiency of development and efficiency of verification are greatly improved.