According to the development needs of in situ monitoring equipment of MOCVD, a multi-functional in situ monitoring probe was designed， which can measure three infrared thermometry with reflectivity correction and reflectivity curve of two different wavelengths, namely: 940 nm/1 550 nm double-wavelength colorimetric thermometry, 940 nm monochromatic radiation thermometry, 1 550 nm monochromatic radiation thermometry, 940 nm reflectivity curve and 1 550 nm reflectivity curve. The test measuring analysis was done for the properties of in-situ monitoring probe, the silicon (111) substrate growing blue light LED epitaxial wafer with InGaN/GaN MQW structure in homemade MOCVD system by using the probe, was monitored on-line. Result shows that the lowest range of three infrared thermometry is equally 435℃; the accuracy within 1℃ colorimetric temperature range from 900℃ to 1 100℃; the repeatability within 0.7℃ from 700℃ to 1 100℃; insentive to changes in height within 2 mm; and the method can avoid the affection of the effective area change of detector aperture. The relative error of n-GaN layer thickness measurement was 3.6% by analyzing 940 nm reflectivity curve. So it can be seen that MOCVD in situ thermometry and film thickness measurement can be achieved by the probe at the same time. The design can provide reference for the developing of MOCVD in situ monitoring device.