This paper describes a study on after-burning suppressant in a solid propellant to reduce the plume formed outside of rocket nozzles, which could expose the launch site and the flight track. The minimum smoke propellant to enhance the stealth ability was formulated in terms of the kinds and the effects of after-burning suppressant on the ballistic performance and the amount of primary smoke.A after-burning suppressant, K 2 SO 4 of about 1.1% weight content was found to show profound reduction of the rocket plume, giving negligibly slight increase in pressure exponent of burning rate.Also minimum smoke propellant with less than 1.1% of K 2 SO 4 corresponds to A-class satisfaction in primary smoke by AGARD standard.