The utility model discloses an adopt device of pressure balance automatic measure soil CO2 gas strength, specifically speaking relate to one kind to adopt the pressure balance principle to gather the tubulose measuring device technical field that the land for growing field crops CO2 of soil lower floor gas carries out determination. Mainly by a tub main part, earth pressure room, on the ground survey the air chamber, inferior high gas dome, mesh air inlet housing, ventilative division board, survey an appearance system composition. Wherein, ventilative division board separates to become the earth pressure room on upper strata and each air chamber of lower floor to the homogeneous tube main part, and the earth pressure room is located on the earth's surface with the survey air chamber, because technique restriction, present soil CO2 gas concentration measurement instrument can't directly imbed the underground and measure, through pack in the earth pressure room with height such as gas dome, with the soil of periphery with nature, utilize the pressure balance principle to come the realization ground to survey the unanimity of the online sample value that the air chamber is surveyed and lower floor's air inlet housing. The utility model has the advantages of reasonable in design, simple structure, measurement are accurate, the disturbance is less, can measure in succession.