The invention discloses a heavy gas leakage diffusion and control study experiment method. The method comprises the steps of executing control technologies via orthogonal experiments to obtain key factors influencing properties and influence degrees; performing fine control experiments according to the obtained key factors to confirm a quantitative relation between the key factors and the influence degrees; performing heavy gas leakage diffusion and control experiments via orthogonal experiments to determine key factors influencing the concentration and distribution of heavy gas cloud under different conditions and influence degrees, tracing the direction of mass energy, disclosing a control mechanism, and seeking an acting relation among the control technologies; and establishing a mathematical model according to the obtained acting relation among the control technologies, key factors and influence degrees, and predicting evaporation rates and down-wind LFL (Lower Flame Limit) longest distance under different environmental conditions, leakage conditions and corresponding control technologies. The method has a very good effect on controlling LNG (Liquefied Natural Gas) leakage harm by studying various control technologies.