This paper introduced a new type DTH hammer drilling with eccentric simultaneous casing about the structure composition and the design idea. In view of the complex situation of working environment and the force features, modeling was made on DTH hammer drilling tool, various load conditions were set and the working conditions of DTH hammer drilling were simulated with the finite element software ANSYS 11.0. According to the results of simulation analysis, improvement was made on the design of drilling tool and the results provide the theoretical basis for rationality and reliability of the new type DTH hammer.