Abstract: The technology of pressure build-up curve was a common technical means in the oil and gas field development, according to the maturity theory and methods of the pressure build-up curves in oil and gas well, the coal seam pressure build-up curves theory and the coal seam gas pressure calculation method using the pressure build-up curves were determined combining with the coal seam gas occurrence and geological conditions. The field tests showed that gas pressure can be determined and measured in short time (the determination period of the pressure build-up curves was 1/10 to 1/2 than the common determination method) by using the coal seam gas build-up curves method, the determination gas pressure was in agreement with the results of the common determination method, the error rate was less than 3.6%.