Abstract: Carbon or its compound formed in the process of oil catalytic cracking reaction, adhering on the catalysts surface, can prevent oil and catalyst from contact with each other. So, the selectivity and activity of the catalyst declined. It can instruct refinerys production effectively that determining the amount of carbon-element in the balanced catalytic cracking catalyst. The data of the precision and accuracy shows that the method, i. e. combustion-and-GC, is one of the effective method measuring the amount of carbon element in the balanced catalytic cracking catalyst.