Four kinds of flame inhibitors with different structure and functionalities, K₂SO₄, KNO₃, new potassium salts AK and BK were selected and the powder charge samples were made using two patterns of adding flame inhibitors in desensitiged and coated course. The muzzle flames were tested with a B-shutter photography method. The effects of flame inhibitor on muzzle flame were experimentally studied. Results show that different adding patterns of the same flame inhibitors have different effect on reducing flame. The effects on reducing flame when adding in the desensitiged course are better than that in the coated course. The new potassium salts AK and BK are not hygroscropic and have better effect on reducing muzzle flame than the common flame inhibitors, K₂SO₄ and KNO₃. Under the conditions of same inhibitor and adding pattern, the more flame inhibitor adds, the better effect on muzzle flame reduces.