In order to effectively simulate irregular wave groups that better represent the characteristics of real waves, a numerical wave tank based on the semi-mixed Eulerian-Lagrangian algorithm and boundary element method was developed in combination with the theoretical generation method of irregular wave groups. Firstly, the impact of model parameters on numerical solution was analyzed. It was found that the accuracy of wave simulation increased with the increase of damping layer length or the decrease of time step. Appropriate deviation distance, distribution range and number of source points can balance computation accuracy and stability. Then, unidirectional irregular wave groups were simulated based on the verified model parameters. The numerical results were compared with the results of physical test and the theoretical values to validate the performance of numerical tank in simulating irregular wave groups. The results indicated that the developed numerical tank can effectively simulate the generation and propagation of irregular wave groups.