It is well known that there is oscillation singularity near the interface crack tip, which is physically unreasonable. A modified interface dislocation model is developed to remove such oscillation singularity for interface fracture. The Dirac delta function in the fundamental solution of interface dislocation is explained by locally-distributed continuous function. The problem is reduced to the solution of a system of singular integral equations. The critical interfacial fracture mechanics parameters, such as the stress intensity factor, the mode mixity and the energy release rates for particular materials group are obtained.