Abstract: The time domain method (TDM) is one of the most effec tive methods to identify moving vehicle dynamic loads from the measured responses of the bridge. However, some problems sometimes occur in the TDM, such as, lower identification accuracy, sensitivity to the noise involved in the measured responses of bridge, and so on. On the basis of the theory of moving force identif ication, the preconditioned conjugate gradient method (PCGM) is proposed in this paper. For twoaxle timevarying moving loads of a vehicle under various noise levels, some illustrative simulation shows that the identified results by the PCGM have higher identification accuracy,stronger antinoise capacity, faster convergence and easy selection of initial parameters. It is beneficial to the practical application of the moving force identification method, particularly for the cases of identification of moving loads only from the measured bending moments.