In view of the real-time requirement of the application of camera position estimation, and of the defect of the RPnP algorithm that it cannot get a unique solution when using the least square error, an adaptive accelerating RPnP algorithm is proposed.When calculating the error, more constraints are added to the least square, and the uniqueness of the output solution is guaranteed. Afterwards, the corresponding camera parameters are calculated, which are used to replace the calculation and comparison process of each minimum reprojection error, and thus can save a lot of time. Finally, the original algorithm and the improved algorithm are adaptively combined to optimize the output results. The experiment shows that this method can greatly reduce the time complexity of the algorithm, and the running time is hardly influenced by the number of points, which is more adaptable to the scene with high real-time requirement.