Objective To study the effect of hemisection in the treatment of the molars. Methods 136 molars were selected and hemisection technique were used. If the pathological change was concentrated to the root, such as periodontics, apical inflammation, root fractures, the pathological root was extracted. If the pathologicalchange was concentrated to the divergence of the roots or the bottom of pulp chamber, hemisection was performed. then all the tooth was restoredwith fixed restoration according to the solid conditions. Results These were followed up and evaluated in three years 94. 85% of the all molars were treated satisfactory. Conclusions The hemisection techniqueoperation is simple, but the indications are extensive,and its effect in the treatment of the molars is regarded as a positive method