In order to study the runway length of military aircraft landing, this paper proposes a calculation method of runway length’s safety coefficient based on safety. The paper mainly analyzes some environmental factors affected by landing quality, wind speed, pressure, temperature, surface friction or longitudinal slope. The paper utilizes Monte Carlo method for simulating the safety landing runway length value and security coefficient which is taking as the ratio of landing runway length and landing running distance. The results show that the safety coefficient of runway length decreases with the increase of landing quality and the higher the safety requirement of the aircraft, the greater the safety factor, but the safety factor will have a marginal value. Under conditions of taking a certain type of military aircraft as an example and setting the environmental factors of the airport, the paper simulates the length of the runway to meet the needs of actual requirements. If the aircraft lands in the maximum quality, when the safety is 99.99％, the safety factor will be 1.40 and the safety factor will be 1.98 in the wet condition of the road surface. The maximum marginal value of the safety factor is 1.43 and 2.02 respectively.