Analysing the change of gas composition in mine closed fire area is the most important basis for evaluating the combustion state of fire area. However, due to the fluctuation of ground atmospheric pressure, the gas composition within a certain distance of the closed wall in mine closed fire area is affected by air leakage, which can not effectively reflect the true state of fire area. Grasping the law of ground atmospheric pressure change is the basis for drawing up the gas sampling scheme in mine fire area. Based on the annual atmospheric pressure hourly recorded data from six surface meteorological monitoring stations in Shanxi Province, China, this paper analysed the diurnal periodicity, annual periodicity, fluctuation amplitude and change rate of atmospheric pressure changes, and discussed and analysed the influence of surface atmospheric pressure variation law on gas sampling method and sampling timing in closed fire areas. The results show that: (1) the variation of atmospheric pressure does not have a diurnal periodicity, but the distribution of atmospheric pressure troughs and peaks is regular in every day; (2) The fluctuation of atmospheric pressure lead to the irregular expansion and contraction of the gas in the closed fire zone. Therefore, in order to obtain the real gas in the fire zone, it is necessary to monitor the pressure difference inside and outside the closed wall, and analyse the pressure difference inside and outside the closed wall synchronously when analysing the gas composition; (3) Continuous sampling and analysis equipment should be used to conduct gas analysis in closed fire area for correct analysis of combustion state in closed fire area. CITATION:Lei, B W, Wu, B, Wang, H Y and Zhu, H Q, 2019. The influence of atmospheric pressure change principles on gas sampling in mine closed fire zone, in Proceedings Australian Mine Ventilation Conference 2019, pp 194201 (The Australasian Institute of Mining and Metallurgy: Melbourne).