All of us are concerning about how to mitigate students’ casualties when an earthquake attacked primary and secondary school buildings. Pupil’s earthquake evacuation simulation for school building was manipulated in this paper: first, we investigated and analyzed earthquake damage of school building, students’ casualties. Second, we established the dynamic model for pedestrian earthquake evacuation; meanwhile, evacuation simulation of 576 school-aged children from grades 1 to 6 who were sitting in classrooms was carried out in the 2014 Ludian earthquake. A range of scenarios (with and without earthquake) was presented where children characteristics (such as size, individual travel speeds for year of different ages), and physical environment characteristics (such as number and size of exits, obstacles including chairs and desks in classroom, walkway and staircase layouts) were investigated. We also considered the building shaking by finite element method during children escaping. The results demonstrated that: total evacuation time for the earthquake scene was longer than that of no earthquake scene, because the floor shaking deferred the evacuation; students cost much more time to escaping from the building which damaged seriously under earthquake; more than 300 students could not evacuate to safe area leading to injuries, which is consistent with the practical situation in the 2014 Ludian earthquake.