IEEE802.16 OFDM system can support wide band wireless multi-service access. Because of its high data transmission rate and strong ability of anti multi-path, it has the good application prospect. The adaptive allocation algorithm can be adopted to raise the frequency spectrum efficiency and satisfy the users' quality of service (QoS). An adaptive resource allocation algorithm based on the IEEE802.16 OFDM system is proposed in this paper. Firstly, each sub-carrier chooses one user who has the biggest intermediate value. Then the bit load algorithm of the single user can be introduced to determine the number of bit and power of each sub-carrier. Finally the resources adjustment can be adopted according to the service priority. The simulation results demonstrate that the transmission rate is higher than comparison algorithm.