【Objective】To investigate the feasibility of making the protocol with computed tomography data for total knee arthroplasty using patient-specific femoral and tibial cutting blocks.【Methods】54 consecutive patients diagnosed with osteoarthritis were divided randomly into two groups. Every patients accepted 3-dimentional computed tomography scan for bilateral legs before operation，the protocol were made for every patients before operation. When making the pre? operative protocol，we accepted the prothesis surpass the osteotomy edge finitely，tibia prothesis rotational orientation according to the outline of the tibial osteotomy. The thickness of the posterior condyle of femur resected was as the same with the prothesis posterior condyle as possible. The patients in trial group undergone total knee arthroplasty（TKA） using patient-specific instruments（PSI）according to the preoperative protocol，while the patients in the control group undergone TKA using custom instruments（CI）. The operation time，the times that the scale of the prosthesis were altered intraoperation，the mean thickness of the posterior condyle of femur resected in the operation，AKS score 3 months and 1 year after the operation were recorded and compared between the two groups. Plain film radiography after the operation were analyzed.【Results】No significant differences were found between two groups with respect to the operation time. 8 patients altered to a lesser prosthesis in the CI group during the operation，all in bibia contrast to no one need alteration in the PSI group. The thickness of the osteotomy on the posterior condyle of femur in the PSI group is bigger than that of CIgroup as a result. The AKS score of the patients in the PSI group is higher than that of CI group 3 months after the opera? tion，whereas no significant difference was found 1 year after the operation.【Conclusion】The reconstructed image by thin layer CT can be used for preoperation protocol for TKA，which might be helpful in deciding the size of femour prosthesis； the implants can surpass the edge of the osteotomy finitely in TKA，which is not necessarily cause any complain. We can orient the tibia prosthesis rotation according to the outline of the osteotomy of the patients’tibia.