Abstract: Using the microscope heating stage with the temperature programming controller developed by ourselves, both the heating behaviors of macerals from Late Permian (P2)and Late Triassic (T,)coals and the microscopic characteristics of coke are observed and studied. on this basis,the cause that the isometamorphic coals from different ages have different cokabilities is revealed,a new concept of standard active component (V,..,)is presented,and the method used to measure the vitrinite reflectance in mixed coal is determined;finally,on the basis of the coke——oven tests with large volume of 200 kg in Coking Plant of Chongqing iron and Steel Company, tising the mathenatical statistics with the computer,three parameters,i. e,standard active component (Vt,st),vitrinite reflectance (Rran)and its standard deviation (S)are optimized, and the mathematical model which can predict accurately and quantitatively the mechanical strength of coke is established. According to the application in the Coking Plant,it is proved that this method used to predict and control the coke strength not only has higher accuracy and simplicity, but also is suitable for the complex conditions that most coking enterprises in our country are supplied by various locanons from different coalfields,the coal qualities are unstable and often with mixed coal.