Up to now, few studies have been performed to evaluate the safety of underground cavern group under earthquake, and most of the researches are limited in a single factor such as stress or displacement. Based on the integrating strength reduction method, particle swarm optimization method, projection pursuit method and set pair analysis model with Vague set, an seismic safety evaluation model with multiple parameters is proposed for huge underground cavern group. In this model, several dynamic response parameters such as vertical displacement, horizontal displacement, acceleration, and compressive stress are taken as the key factors to evaluate the seismic safety of underground caverns. A multi-index seismic safety assessment method system is hence proposed for large underground cavern group in this paper. A case study is performed to evaluate the seismic safety of the underground cavern groups of a huge hydro-power project, the results show that the selected three sections of the underground caverns are all in a safe and steady rating, which in turn demonstrate the effectiveness of the proposed model.