Traditional Receiver Autonomous Integrity Monitoring (RAIM) algorithm uses integrity risk minimum criterion to determine the threshold,the threshold solving method is too conservative and may increase the risk of the continuity to aviation users.In view of the differences between the aviation users integrity requirements,a RAIM threshold optimization algorithm based on minimum total risk cost function is proposed.Taking the sum of false alarm probability and missed detection probability in hypothesis test as the total risk cost function,on the premise of ensuring RNP and RAIM availability,the total risk cost function is minimized to determine the RAIM optimize threshold and achieve the trade-off between integrity and continuity.The simulation results show that after the minimum total risk cost function trade-off,the continuity risks of users can be reasonably reduced,and the RAIM availability can be judged in the pseudorange domain.