Purpose: The instrument is suitable to calibrate and check all kinds of inclinometers to determine measurement accuracy of dip angle and azimuth angle of inclinometers. Main technical characteristics: 1. Each scale division of dip angle dial is 1°; error among scale divisions is not more than ±3′; measurement error using a vernier: ＜±6′; 2. Each scale division of azimuth angle dial is 2°; error among scale divisions is not more than ±3′; measurement error using a vernier: ＜±12′; 3. Sensitivity of water level bubble is 4′; Error: ＜±20%; 4. It can clamp inclinometer with a diameter of φ62-φ76 mm; 5. The non-verticality error between the horizontal axle and central axle and between the vertical axle and the central axle is less than 12′;