Abstract: The PnP problem is a widely used method in pose determination since it is a single-view based approach and does not need any image point correspondences, a difficult task itself in computer vision. The multiplicity and stability of solutions in the PnP problem are two important issues, they somehow directly determine the sucess or failure of a real application. Then questions arise: What is the distribution of the multiple solutions? Does the exsistence of multple solutions necessarily mean that the solutions are not stable? There are no related reports on such issues in the literature to our knowledge. In this work, these two issues are investigated in terms of P3P problem, and the obtained results could provide some insight for the problem of the multiplicity and stability of the PnP problem, and could be of reference to the people in the field.