Abstract: Aiming at the scenario of Small cell under aggregate interference, the performance of micro base station locations follow Poisson distribution and the precoder of MU-MIMO adopts linear precoding was analyzed. The closed-form expression of outage probability, system capacity and symbol error probability of Small cell were derived, the results revealed that the performance of user can not rise continuously with the Small cell base station antennas increasing because of the existence of aggregated interference. Furthermore, the user access mechanism based on energy efficiency was proposed in order to solve the Small cell user access problems, the theoretical analysis were derived and verified via simulations, the results show that the scheme proposed can improve the system energy efficiency performance and was superior to the other access schemes, which can verify the superiority of the access scheme based on maximum energy efficiency and correct theoretical analysis.