Integer least square problem is widely used in wireless communications, cryptography and some other fields. In this study, the authors propose a radius bisection algorithm with restart strategy to solve the ILS problem. Compared with the original sphere-decoding method, the algorithm can solve the ILS problem with higher speed and lower complexity. Also, users can specify a stop criterion to control the accuracy and complexity of the algorithm. Finally, some simulated experiments show the efficiency and effectiveness of the proposed algorithm.