Based on studying the previous research achievements in active tectonic of the Yingxiu-Beichuan fault in the Longmen Mountains, measuring the offset dates of the surface ruptures of the Wenchuan earthquake, and making activity segmentations to the Yingxiu-Beichuan fault, this paper uses the calculation methods for earthquake magnitude to assess the magnitudes of the coming earthquakes in the Yingxiu-Beichuan fault and estimate the recurrence intervals of the strong earthquakes in Longmen Mountains. The results show that the estimations of the magnitudes are 7.15±0.35 in the Xuankou-Xiaoyudong segmentation, 7.36±0.33 in the Xiaoyudong-Leigu segmentation, 7.30±0.39 in the Leigu-Shikan segmentation, 7.62±0.41 in the Yingxiu-Beichuan fault belt for the coming earthquakes, and the estimation of recurrence interval of the strong earthquakes is 1 310~3 932 a in Longmen Mountains.