The utility model relates to a three-axis sensor mounting device, and belongs to the field of auxiliary tools. The installation device comprises a containing frame and a placement rod connected to thecontaining frame. A frame body of the containing frame is a pentagonal frame body formed by obliquely cutting a right angle on a rectangular frame body, the horizontal section of the frame body is apentagon with four right-angle sides, and the longitudinal section of the frame body is rectangular. The placement rods are fixedly arranged on the outer side of the frame body of the containing frame. According to the installation device, the installation difficulty of the three-axis sensor can be greatly reduced, the directivity of the three-axis sensor is guaranteed through the containing frame, and when the direction of the three-axis sensor needs to be adjusted, the position and the angle of the containing frame can be manually adjusted only through the placement rod. On one hand, the adjusting difficulty is reduced, and the adjusting time is shortened; and on the other hand, the three-axis sensor can be conveniently taken out and replaced.