Abstract: In order to solve the problem of excessive complexity of the adaptive bit allocation algorithm in the orthogonal amplitude modulation-orthogonal frequency division multiplexing modulation (QAM-OFDM) system, an adaptive bit allocation algorithm is proposed. Based on the edge adaptation criterion, with the preprocessing of the channel gain, the iterative allocation uses AND operations and shift operations to reduce the calculation and sorting operations in the greedy algorithm. In the same simulation environment, the simulation results show that the improved algorithm has almost the same bit allocation effect as the greedy algorithm, and it takes less time than the greedy algorithm, thus verifying that the improved algorithm has high practicability.