The invention discloses a position 
privacy protection method based on dynamic pseudonyms. The position 
privacy protection method mainly overcomes the defect that the position 
privacy protection degree in an existing position pseudonym method based on position services is too low. The position privacy protection method comprises the steps that a communication 
system composed of users, a credible mechanism and a 
service provider is built; the 
system is initialized through the credible mechanism; the users sign in the credible mechanism on line to obtain public and private keys; the credible mechanism updates the pseudonyms and pseudonym certificates of the users regularly; the users use the dynamic pseudonyms to request position services from the 
service provider; the 
service provider provides service data for legal users and requests the credible mechanism to revoke malicious users; the legal users obtain the position service data. According to the position privacy protection method, identity 
anonymity is achieved by using the dynamic pseudonyms, the relation between identity information and spatiotemporal information is 
cut off, and therefore it is difficult for the service provider to speculate position information of the specific users by means of 
side information, position privacy of the users is protected effectively, and the position privacy protection method can be used for position privacy protection based on the position services in social networking services.