Total sacrectomy is a useful method to treat the tumors which involve the first sacral vertebra. After operation, the destruction of pelvic ring often result in the separation between lumbar and pelvis, which need to be reconstructed clinically. But the loosening and fracturing after reconstruction could often occur. In order to evaluate the clinic work for reconstruction and to solve the stress concentration after reconstruction, finite element methods are commonly used to offer reliable basis for clinic study. The author reviews the recent advance in constructions for intact pelvis model, the defect model after sacrectomy, and the model after reconstructing lumbosacral spine to give a general summarization.