In controlled blasting, pre-cracks are often used to reduce the blasting vibration hazards. In this paper, with the engineering of 3 # on-line repair in one large iron and steel group in China, the kinetics of the steady one-dimensional shock wave, transmitting through the pre-cracks in near field from the blasting piont, were analyzed. And the damping effect was calculated too. Small-scale industrial test was conducted. These provide a reference for the blasting design.