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Joint is an important factor to control the stability of surrounding rock.How to simulate the propagation and connection of joint network in natrue is the diffucult and key point.In this paper, a new numerical method to simulate crack propagation is proposed—the Meshfree Discrete Element Method (MDEM), combining the advantages of the Meshfree Finite Difference Method (MFDM) and the Combined Finite-Discrete Element Method (FEM/DEM).In the proposed MDEM method, the displacement gradient and velocity gradient is caclulated in each discrete block using weight function and shape function.The weight function is modified from a singular function.And the shape function, which is like δ function, is a modified form of zero order Moving Least Square shape function.Contact criterion is also modified on the basis of MFDM and FEM/DEM here.The MDEM method is less time cosuming and more acurate.Also, boundary conditions can be added more conveniently and crack growth is independent with the meshes with the MDEM method.Then, the implementation of MDEM method is done and the accuracy of it is verified with a typical example: the cantilever beam bending test.With the MDEM method and a failure criterion (the strain softening based smeared fracture model), the crack growth can be simulated.Crack propagations in finite thin plate with a horizontal centre crack and finite thin plate with an inclined centre crack are simulated respectively under tension load.The stress distribution in crack tip and crack propagation path are studied.It is concluded that the numerical results were similar to the theretical results for stress distribution in crack tip.