The utility model discloses a laser gas detection device. The light-sensitive surface of the device and the termination section of a preset optical path are crossed and are not perpendicular to each other, so that a laser transmitter emits detecting laser from a transmitting terminal, the detecting laser can be projected to the light-sensitive surface of a laser receiver along the preset optical path; in the process of detecting laser projection, the detecting laser fills to-be-measured gas in the preset optical path along the way, and the termination section of the detecting laser projected to the light-sensitive surface can reflect related parameters of the to-be-measured gas; at the time, though the light-sensitive surface can perform reverse reflection on the termination section of the detecting laser, the light-sensitive surface is not perpendicular to the termination section of the preset optical path, light undergoing reverse reflection from the light-sensitive surface cannot perform perpendicular incidence or reach the transmitting terminal through the reflection, and accordingly the interference of the transmitting terminal of the laser transmitter caused by the reverse reflection light is avoided.