Abstract: With the continuous advance of engineering geomechanics and its related disciplines as well as unceasing resolution of relevant problems,the engineering geomechanics is now entering into a new development stage. This paper summarizes brilliant achievements and great challenges for this discipline in the 20th century and then presents its theoretical system in detail including structure relativity of engineering geological mass,continuity of engineering geological mass,constitutive relation of engineering geological mass,large deformation of engineering geological mass and large-deformation design method of engineer geological mass, et al. At last,great prospects for engineering geomechanics have been proposed in many aspects such as research of material control in large deformation disaster,engineering disaster control,energy constitutive relations of engineering geological mass,energy equilibrium equation of engineering geological mass and trend of quantitative design in geological engineering. Basing on all of discussions,we should be aware that the task of engineering geomechanics workers has far to go.