The theory of pyrotechnic cutting was analyzed by heat transfer theory and mechanics, the reason and solution of the main influencing factor of pyrotechnic cutting effect were studied. Considering both price and toxicity, and the adiabatic reaction temperature of pyrotechnics was calculated by chemical thermodynamics, the thermites with adequate heat were screen out. By experimental observation of the combustion of thermites, two kinds of thermites that are appropriate for pyrotechnic cutting were determined, which are cupric thermite and ferric thermite. By uniform designed experiments, the good formula of pyrotechnics that is used for melting metal material was obtained. Which is composed of ferric thermite 30%~50%, cupric thermite 30%~50% and other thermite 10%~20%. The pyrotechnics can generate high temperature and high speed melting jet of Cu-Fe alloy, which can cut metal material effectively.