The present invention provides a collaborative positioning method and system, positioning device and storage medium based on three-dimensional map assisted GNSS, combining ray tracing algorithm and double difference method, using ray tracing algorithm to obtain the absolute position of road users, uniformly gridding the area where road users are located, performing NLOS error correction on the pseudo-range of the grid to obtain correction values, randomly pairing the grids belonging to different road users in pairs, using the double difference method to calculate the pseudo-range correction values of the grids, and calculating the posterior probability of the grid pair, and calculating the weighted average of the relative distances of the grid pairs to obtain the relative distance of the two road users, thereby correcting the error caused by the NLOS effect and other abnormal errors; introducing a factor graph as an optimization decision for the positioning problem, determining the uncertainty of each constraint, and calculating the positioning result through a cost function.