Numerical prediction of the acoustic radiation of vibrating engine block is conventionally based on the boundary element method (BEM). This approach yields good predictions, provided that the dynamic behavior of engine block is well established. However, interior resonances may lead to singular matrices and nonunique solution. To avoid the problems with interior resonances and singular matrices, this paper introduced the combined Helmholtz integral equation formulation method (CHIEF METHOD). The numerical experiment shows the performance of CHIEF METHOD and then we use this method to estimate the acoustic radiation of engine block. Based on spatially mean square velocity and acoustic radiation efficiency of vibrating engine block, a simplified analytic method is presented in this paper, by which the vibrate induced noise can be predicted in the early design process of engine development.