Based on strain modal assurance criterion, a model updating method is proposed. Strain modal assurance criterion, on one hand, is a satisfactory approach to evaluate the correlation between finite model simulation and experiment. On the other hand, strain modal assurance criterion offers global frequency error and local mode shape error for model updating. The basic theory of strain mode and finite element model updating is briefly introduced. Then, take a stiffened structure as example, the process of model updating based on strain mode is illustrated. Firstly, strain modal frequencies and mode shapes are obtained from simulation and experiment, respectively. And then, modal assurance criterion of strain modes and error of modal frequencies are calculated. The objective function for model updating is constructed based on above errors and unknown parameters are estimated utilizing genetic algorithm. Finally, the estimated parameters are substituted into the finite model to validate the accuracy and effectiveness. The results show that: the proposed method can reproduce the response in the updating domain and have an excellent ability to predict the response outside the updating domain.