Abstract: In this paper， we used the elastic constitutive relation to simulate the effect induced from the Indian plate everlasting northward collision on the Bayan Har block and surroundings on the Qinghai--Tibet plateau. By reducing the element elastic modulus at the earthquake location， a number of numerical simulations have been made for the strong earthquakes (M_S≥7.0) since 1900， and also for the influence from the former earthquake on the latter. We obtained the following results: ① The background stress is higher in the west as expressed in equivalent stress， and decreases gradually to the east; in the middle-west of the block the stress level decreases gradually from south to north with equivalent stress obviously low in the east. ② In the strong earthquake series eight earthquakes were triggered before their occurrence and three were delayed， while other two were in the sress transition zone. ③ From the stress interaction between the strong earthquakes before and after 1970， we may conclud that the historic earthquakes triggered the 1973 Yijitaicuo earthquake， the 1997 Mani earthquake and the 2001 Kunlun Mountain Pass earthquake， while the influence of Kunlun Mountain Pass quake on the Wenchuan quake is insignificant， and the effect of Wenchuan quake on the Yushu earthquake is unobvious.