Abstract: Purpose: To explore a novel method of accurate measurement of patient with knee varus and valgus though computer assistant and the value been evaluated. Method: 14 patients admitted from Sep, 2010 to Sep, 2013, included 16 knees, consisted of 10 varus knees and 6 valgus knees. With computer assisted, appropriate osteotomy site and angle were selected and operation method planned. After operation, HSS evaluation was done compared with those scores before operation. Result: All patients were followed up between 3 to 12 months, the varus and valgus angle were quite well corrected, and the lower limb power lines were rebuilt. HSS scores were elevated from 52.6 ± 13.1 to 86.2 ± 8.9, respectively. Only 1 patient found infected, and cured with antibiotics. Conclusion: It is a valuable method to help a surgeon to make an operation plan for patients with knee varus and valgus diseases.