：In order to improve the accuracy and effectiveness of structural model updating, a finite element model updating method based on modal parameters and a modified firefly algorithm is proposed, in which an objective function based on modal parameters is formulated and solved by the modified firefly algorithm. The modified firefly algorithm is compared to be accurate and superior to the original firefly algorithm, genetic algorithm, and particle swarm optimization in solving a numerical simulation example of a truss model. And it shows that the optimal solution obtained by the modified firefly algorithm is closer to the actual value, and the scatteredness is low, which proves the accuracy and effectiveness of the modified algorithm. Finally, the accuracy and effectiveness of this method in structural finite element model updating are verified by a damage identification test of a 6-DOF shear frame experimental model.