The integrity parameters of BeiDou satellite navigation system include user differential range error (UDRE), regional user range accuracy (RURA), and grid ionosphere vertical error (GIVE). In this paper, the algorithms about UDRE, RURA and GIVE are researched, the variation of the UDRE and RURA in a whole day are analyzed and simulated, the variation curve of the GIVE in a whole day is presented about ionospheric grid point(IGP) No. 97(40?N, 115?E), and the feasibility of the algorithms are verified. The simulation shows that the algorithms of UDRE, RURA and GIVE can limit the equivalent clock error and the grid point ionospheric delay error with a confidence level of 99.9%, and reliable integrity monitoring can be provided for users by these parameters.