In this study, we dealt with numerical analysis of the velocity distribution in the flow of gas-solid mixture about the various shapes of supersonic convergent-divergent nozzle by using the computational fluid dynamics CODE, FLUENT^TM. We also studied grinding characteristics of a target-type jet mill. It was found that the results of the present numerical analysis and experiment were in good agreement. We could select the optimum nozzle shape with respect to the grinding efficiency. And then the optimum grinding conditions were investigated with respect to the following parameters : the grinding pressure, the distance from the nozzle outlet to the target plate, the angle between the jet flow direction and target surface, and the mixing ratio by weight. The results show that the optimum conditions of the collision length, target angle, and mixing ratio are 2-3 times the distance of the nozzle outlet diameter, 60-90。, and < 0.5, respectively.