Based on analyzing the resource allocation model in wireless Ad Hoc networks, a QoS-aware cross layer resource allocation algorithm, CL-QARA (cross layer QoS aware resource allocation) algorithm, is proposed. The purpose of CL-QARA algorithm is to introduce price and QoS bandwidth to measure resource allocation. The dynamic resource allocation information in the network layer is combined with the CSMA/CA admission control in the MAC layer to improve the backoff algorithm. A new backoff algorithm and call admission control algorithm is designed to implement a cross layer technique between the MAC layer and network layer. The QoS-aware resource allocation algorithm cooperates with the cross layer technique to provide the QoS guarantee. The simulation results show that CL-QARA has good convergence and stability. Compared to other algorithms, CL-QARA provides better QoS guarantee. CL-QARA also improves the network utility and performance.