The invention discloses a method for establishing a rock material ageing and elastic-plastic mechanics constitutive model. The method includes the steps that the triaxial short-long term test result of rock is used as the basis first, and the volumetric strains of a rock test piece under different test conditions are calculated; by drawing a stress-axial and lateral strain relation curve and a stress-volumetric strain relation curve, the yield criterion, the non-associated flow rule and the hardening criterion of the rock are determined, and an elastic-plastic mechanics model is established; then by combining material micro and fine damage attenuation ageing evolution dynamic equilibrium, the micro and fine ageing damage rule of the rock is determined, the model is popularized, a relation matrix of strain increment and stress increment at the ageing-elasticoplastic deformation stage is established, and accordingly the rock material ageing and elastic-plastic mechanics constitutive model is obtained. According to the model, the mechanics significance is definite, the expression is unique, the number of parameters is small and can be obtained based on the test results, hence, solving uniqueness and accuracy are guaranteed, and wide applicability and expansibility are achieved.