In order to evaluate the impact of mud cake thickness on shearing strength at cement-formation interface accurately, a feasible simulation experiment system and evaluation method was established, which includes preparation of artificial core, formation of mud cake, maintenance of the samples and testing of the Shear bond strength of cement-formation interface. Based on this, by taking commonly used drilling fluid from Shuangjiang oilfield, Jinglou oilfield and Zhongyuan oilfield in China as examples, the laboratory impact evaluation results show that: (1) As for different drilling fluid system, the shearing strength at cement-formation interface of the cement-formation interface keeps a general tendency to an obvious decline as the growing of the mud cake thickness. (2) In the same drilling fluid system, though different in the time of maintenance, the variation trends that the shearing strength at cement-formation interface declines as the growing thickness of the mud cake are similar. (3) The declining rate of shearing strength at the cement-formation interface will reach 83.4 %-99.9 % when the mud cake thickness is 5mm. These developments of this paper can be used to optimize the design of drilling fluid and cementing technology, and consequently improve the cementation quality of cement-formation interface to meet the demands of highly-efficient petroleum production.