Objective: To investigate the treatment for complex fractures of the knee.The authors put forward internal fixation classification and reviewed 42 cases with complex fractures of the knee from 1994 to 1999. They were treated by classified-internal fixation with manifold equipments of internal fixation.Results:The follow-up were 6 to 60 months.Of these,good result was 80.1%.Conclusion:Open reduction and classified-internal fixation may be uesd for treatment of the complex fractures of the knee.The authors suggest early functional exercises and CPM after operation,The authors put forward that internal fixation classification has an important reference value for formulation of the scheme of treatment.