Organic carbon (OC) and elemental carbon (EC) in atmospheric aerosols play a major role in environment, climate and human health effects. At present, thermal-optical method is acknowledged to be a more mature method for measuring the OC and EC, which can be divided into two methods, thermal-optical transmission (TOT) method and thermal-optical reflectance (TOR) by the optical correction way. Theory of the two methods is almost the same, but the measuring results are different obviously. Therefore, a thermal-optical transmission and reflection simulating experiment platform are developed by deeply understanding the theory of thermal-optical method. Through contrast experiment, it is indicated that the reason leading to the obvious difference between the two methods is that TOR laser split come more early than TOT.