Aiming at the existing problem in blasting vibration velocity calculation, a calculation method by two steps is proposed, in which the shock pressure induced by explosion is first calculated in blasting near region, then the particle vibration velocity farther is calculated. The damping problem in dynamics calculation is discussed preliminarily. The vibration velocities of the different particles under the three different charge conditions with different intervals such as rock powder, water and air, are respectively calculated by means of the proposed method. The calculated ground vertical vibration velocity under the rock powder interval charge condition is maximum, that under the water interval charge condition is inferior and that under the air interval charge condition is minimum. Calculated results accord with the experimental results.