Abstract: In order to solve the problem that in the process of gas transmission in negative pressure bundle tube monitoring system, the composition and monitoring value of the concentration for gas were easily distorted and sampling lag time was long. A positive pressure bundle tube monitoring system was developed based on the condition that the positive pressure transport was used as the transport mode of detecting gas. The output pressure of positive pressure pump was calculated theoretically, and the lag time and flow rate of the gas sample transmission were tested under different lengths of the negative pressure section bundle tubes. The theoretical calculation and test results show that the output pressure of the positive pressure pump should be 0.75 MPa, and the length of the negative pressure bundle tube should be less than 320 m. Positive pressure gas transmission test was carried out by using positive pressure bundle tubes with different lengths. The experimental results show that the lag time of gas sample transmission is only 872 s in the case of a tube length of 200 m in the negative pressure bundle tube and a length of 5 000 m in positive bundle tube. It fully meets the accuracy requirements of bundle tube monitoring system.