The utility model relates to an automatic gas sampler, comprising a base frame, a sampling unit, a locating device, an actuating mechanism, a support apparatus, a monitor and a power source. The sampling unit is composed of a group of sampling magnetic valve, a gas recovery pump, a needle head base, an injection head (installed on the needle head base) and a plurality of the sampling receptacle. The locating device is composed of a rotating & rise-fall paraxial (mounted on the base). The paraxial is horizontally mounted with the stands for the upper & nether cylinders and a bottle clamping arm. The stands for the upper & nether cylinders are respectively equipped with the cylinder permanent seat. The actuating mechanism is composed of an inflation pump, a needle insertion magnetic valve, a needle withdrawal magnetic valve (mounted on the base) and a two-way cylinder (mounted on the cylinder permanent seat). The support apparatus is composed of a main shaft, a positioning disk, a guide arm and a sample tray. The main shaft is mounted in the middle of the base frame, while the positioning disk and sample tray are installed on the top of the base frame. The super-face of the positioning disk is arranged with a spiral guiding groove, of which the gears are available. The monitor is used for the sampling control apparatus and the actuating mechanism. This utility model is applicable to the air quality sampling & monitoring for the environment protection.