本文针对 Craig 法在计算模态振型时精度不够理想这一问题,通过对 Craig 法的动力学原理的分析,找到了问题的原因。在引入“剩余约束模态”这一新概念的基础上,提出了一种新的改进方法,并计算了一个典型算例.结果表明用改进后的方法计算所得振型的精度较之原法计算所得振型的精度有了较大的改善,符合实际工程的要求。 In this paper, the Craig method is not very accurate when calculating the mode shapes. Through the analysis of the Craig method’s dynamic principles, the cause of the problem is found. Based on the introduction of the new concept of “residual restraint modality”, a new improvement method is proposed and a typical example is calculated. The results show that the accuracy of the vibration mode calculated by the improved method is better than the original method. The accuracy of the calculated vibration mode has been greatly improved and meets the requirements of practical projects.