Abstract: The correct selection of rock mass mechanical parameters is the key and basis for slope stability calculation，which directly affects the accuracy of stability calculation results. Taking an open-pit mine as the research object，on the basis of indoor rock mechanics test data，empirical reduction method， Fisinke method，M Georgi method and Hoek-Brown method are used to obtain rock mechanics parameters and carry out comparative analysis.The research shows that the mechanical parameters of rock mass obtained by using empirical reduction method alone for an open-pit mine are inconsistent with the actual situation. Combined with the practical experience of engineering，the calculation results of the four methods are comprehensively averaged to obtain the mechanical parameters of rock mass suitable for this open-pit mine，which provides reliable calculation parameters for further slope stability analysis.

Key words: open-pit mine, slope engineering, rock mechanics parameters, strength reduction