Abstract: According to the development needs of online infrared thermometry of metal organic chemical vapor deposition (MOCVD), integrating the character of Thomas Swan CCS MOCVD reaction chamber, and considering the particular conditions of the process of heating ratio control vacuum calcination, a simple 940 nm infrared thermometry apparatus was designed, which can measure the surface temperature of MOCVD graphite plate and the radial temperature profile at 19 probe points online. The infrared radiation intensity of the high-temperature graphite disk and the epitaxial wafer was detected by an infrared probe installed above the optical window, and the temperature was measured according to the Planck blackbody radiation formula and the spectral emissivity correction. The infrared temperature measuring device is mainly composed of a readable track, an infrared probe, a connecting plate, and a precision translation stage. The apparatus was used in the process of silicon(111) substrate growing epitaxial wafer with InGaN/GaN MQW vacuum calcination by MOCVD. Result shows that the lowest range of thermometry is equally 430℃; the accuracy is within 2.3℃ from 700 ℃ to 850℃, the accuracy is within 1℃ from 900 ℃ to 1100℃, the repeatability is within 0.6℃ from 700 ℃ to 1100℃. The apparatus work stably, without the need for reflectivity correction and effective hole area calibration.