Physical model tests and their numerical simulations of in-situ rock shear test are carried out to reveal shear behaviour of discontinuous rock masses. Particularly, a comparative study of physical and distinct element simulation of in-situ shear test on steeply dipped stratified discontinuous rock masses are made. In the physical model test where dip angle of the major discontinuity is 70 degrees from horizontal plane, shear stress - displacement relation agree with that of the in-situ shear test. The resultant shear behaviour is observed to be ductile and a kinked yielding point appears before failure. However, influence of the discontinuity on the shear strength is small. It is clarified that the ductile shear deformation of steeply dipped stratified rock masses may be caused by progressive failures. The DEM analysis also successfully simulates the shear behaviour of physical model test. The failure mechanism is quite well revealed as the results are comparable.