A new finite element model updating method is presented using modal frequency and effective modal mass as objective function with genetic algorithm. The effective modal mass can not only provide a method for judging the significance of a vibration in structural dynamics, but also can provide more useful information for model updating. The concept of effective modal mass and the process of model updating with genetic algorithm are introduced. The effectiveness of the method is tested on a simulation example, and the results show that the maximum errors of updated parameters is-0.062％ and the root mean square (RMS) errors for both the modal frequency and the effective mass are less than 0.025％ on the estimated modal parameters. The study demonstrates that the finite element model updating method using effective modal mass with genetic algorithm is feasible and effective.