Objective To explore the effects of different sitting postures on compensatory characteristics of the spine and pelvis, and provide the theoretical basis for finding an ideal sitting posture, reduce posture compensation caused by inappropriate sitting posture. Methods The parameters of surface morphology and hip pressure from 20 healthy young adults in upright sitting, cocke-legged sitting and cross-legged sitting were measured using Diers formetric and Pedscan modules. Results Compared with upright sitting, cocke-legged sitting led to pelvic posterior tilt, lateral tilt and relative torsion (P<0. 05). The pressure area of the cocke-legged hip decreased (P<0. 05), the maximum pressure and average pressure significantly increased (P< 0. 05). The maximum pressure ratio, average pressure ratio of both hips (P<0. 05) as well as symmetry of pressure areas (P<0. 05) for both hips were reduced. Compared with upright sitting, the sagittal plane deviation angle in crosslegged sitting increased ( P < 0. 05), with the trunk flexion, the lumbar kyphosis ( P < 0. 05), accompanied by pelvic posterior tilt (P<0. 05), and pressure areas of both hips decreased (P<0. 05). Conclusions Among three kinds of sitting postures, the upright sitting can be considered as an ideal sitting posture with the uniform force on both hips, the optimal surface morphological parameters of the back, and the least compensation in the lumbar and pelvis.