Abstract: In this paper,the basic principle of γ -ray transmission technique is introduced. Through the study of single tube coking experiments,the possibility of the application of γ -ray transmission technique in furnace tubes is also discussed. The effects of cracking temperature,retention period and steam dilution ratio on coking rate are investigated .Comparing to the results by means of coupon weighing weight, γ -ray transmission technique is feasible for coking measurement. The results are consistent with other reported data in literature.