Abstract: In our pipelining of crude oil, accidents often arise due to coking around the coils of heater. Having cited and aualyced some heater accidents such as coil coking, breaking and firing, the article points out the law by which heater coil coking occur, analyses the compositions of the coking matter, and find out the factors that lead to coking. It is concluded that to prevent coils from coking, the fire wall should be removed and periodlcal checking and inspecting system established. Of course, the thorough way is to introduce the indirect heating system or new type of heater in order to eliminate this kind of accident once and for all.