Based on the index data of primary red clay samples from a site in Kunming, this paper studied the relationship between its physical and mechanical parameters. The physical and mechanical parameters of the study object were analyzed by the methods of laboratory tests and in-situ tests in combination with statistical theory. The results show that the mechanical properties of the primary red clay in the study area are related to some physical properties. The mechanical properties decreased significantly with the increase of water content, and the relationship between cohesion and water content could be characterized by linear function. The elastic modulus decreased exponentially with the increase of water content. The results are of great significance for accumulating the relationship of parameters and improving the prediction of physical and mechanical parameters which are difficult to obtain by using known parameters.