We consider the admission control of small cell access points (SAPs) supported by wireless backhaul in a heterogeneous network. The SAP admission control in wireless backhaul is performed at the wireless backhaul hub (WBH), which aims to serve as many SAPs as possible with the guaranteed data rates. Such a problem involves joint design of transmit beamformers, power control, and selection of SAPs, which is difficult to solve. We propose a low-complexity iterative algorithm that exploits the Karush-Kuhn-Tucker (KKT) conditions of the convex relaxed problem. Such an iterative algorithm converges locally to the optimum solution of the relaxed problem. Based on the outputs of the iterative algorithm, selection of the SAPs is performed. Simulations show that the proposed algorithm is fast and achieves near-optimum results in the cellular setup.