Abstract: Based on the detailed research on EPON system which emerging in recent years,this article focuses on the special point to multi-point topology in EPON system,and one point to multipoint control protocol(MPCP)which used for controlling and managing the EPON system has been discussed in detail.MPCP includs the structure of the 5 controlling frams and the meaning of each code.The principles of starting registration,ranging compensation time delay compensation and time slot allocation are also analyzed in this paper.