Abstract: By considering the influence of end face morphology on the sealing performance and the processing cost, the relationship of between the fractal parameters of the end face and the leakage rate was analyzed by the fractal geometry theory, and a concept of fractal dimension of seal end face of contacting mechanical seal for cost-effective finishing was put forward. The sealing performance was tested and the end face topography was measured for a GY-70 mechanical seal. It is found that both the increasing rate of seal face fractal dimension and the leakage rate were gradually decreased with the running time. When t=130h, Q reached the allowable leakage rate 5?10-6m3/h and D was equal to 1.645. The research results indicated that there existed a fractal dimension of seal end face for cost-effective finishing contacting mechanical seals which wss correspondent to the allowable leakage rate. Reasonable design of fractal dimension of seal face can avoid blind improve machining precision, shorten the running-in stage and acquire good result of initial seal.