Studying hadrons and their characteristics has long been used to better understand the QCD theory. Hadrons are usually studied in vacuum, but since twenty years ago there has been an effort to study the effect of temperature on hadrons. In the following research, the effect of temperature on the mass and the decay coefficient of K .2 , f 2 and a 2 mesons are studied through Thermal QCD law. In this method, the calculations are pretty much similar to QCD method, and our work starts with a correlation function that included theoretical and phenomenological parts. Calculations of the phenomenological part are completely similar to those of QCD with the exception that in the theoretical part, the temperature is included in the expansion section. Finally, we connect the two parts using dispersion relation, and calculate the mass and the decay coefficient of tensor mesons and the effect of the temperature on them. the interesting point is to note the temperature in the calculations, exposure to critical temperature, which is then changed by the nature of the Hadron. One application of this approach is to use better understand the result of experiments of heavy ions.