When measuring the temperature of the object,if the temperature of the measured object is near the environment temperature,then the environment factor has greater influence on the measuring result.In order to enhauee the accuracy of measurement,accoding to the Plank law and through value calculation,the value of the ratio of the environment temperature influence under different temperature of the object,the environment temperature and the radiation wave length and the relation among them have been obtained.Base on the above,and if the influence of the environment radiation can be ignored,the lowest temperature of the measured object is acquired.The enoironment radiation influence on the colorimetric temperature measurement is discussed at last.