According to the strongpoint and shortcoming of all kinds of plane joint elements and theirs applicable range, the basic theories of plane joint elements were introduced in brief. An example which utilized different plane joint elements to simulate the different sorts of discontinuity interface in rock mass was given, and the analysis result indicates that if only the constitutive model of a material is confirmed ,and some special element types are adopted,with the basic principle and approach of the finite element to simulate rock materials, a more satisfactory result can be obtained.