The MCDS of magneto-optical crystal is a very tiny effect. Measurement of polarization of light from stoke parameter is a very accurate method, so it can response to this tiny effect. But it requaire to process so much data and make it impossible in practice. Optical Multichannel Analyser is a very powerful instrument can acquire and process a lot of data. We make a measurement of MCDS and MCBS of (BiTm)3(FeGa)5012 by Stoke parameter use OSMA.The result we obtained conform to the theory, that developed by previous contributor.