Abstract: Based on the conception of shape parameters,the yield function of the modified Cam-clay model is modified.The secondary development in FLAC3D is made.Some conclusions are drawn as follows.Firstly,the yield function generalizes that of the modified Cam-clay model.Secondly,it is very important that the shape parameters correctly predict characteristics of soils.More exact values can be obtained when suitable shape parameters are applied in the model than those in the modified Cam-clay model,namely,the problem that the values gained by the modified Cam-clay moded are larger than those of examinations is solved.Thirdly,through comparison of the results of the inherent modified Cam-clay model in FLAC3D and the proposed model with shape parameters,the validity and rationality of the secondary development is validated to some extent.Finally,it extends the application range of FLAC3D in the field of geotechnical numerical simulation,and may present references for the secondary development of other geotechnical constitutive models.