A statistics-based P-persistent CSMA algorithm is proposed from the study of the CSMA algorithm. That means in such a case that bus contention is unavoidable, the probability of the sending date by devices on the bus is not invariable, it calculates the frequency of every device in a statistical cycle, and the device dynamically adjusts P-persistent CSMA algorithm according to the frequency. The conclusion is: compared with the general CSMA algorithm, the statistics-based P-persistent CSMA algorithm makes the device automatically adjust and send the probabilities in the case of uninterrupted system operation. It is more consistent with the equipment operation to the actual situation, so it is more efficient