Abstract: In order to research gas distribution laws in abandoned roadway of residual coal mining area, calculate the remaining amount of gas in abandoned roadway after fist mining, through theoretical analysis and calculation, we got the formula of the amount and remaining amount of gas in abandoned raodway after fist mining, and obtained the gas accumulation laws in confined space. The results showed that the amount of gas released from coal wall to the abandoned roadway after fist mining is a function of gas migration time, and according to the different gas migration time, the calculation formulas of gas emission are different. Through measuring gas emission and gas pressure in abandoned roadway at the scene of the project, we verified the correct of the formula.