Abstract: This Paper compared the performance of CRDM using metal bobbin coils with those using the traditional non-metal bobbin. From the test result, CRDMs with both kinds of coils can carry out their function correctly and all parameters are well within the specification. But metal bobbin has many advantages over non-metal bobbin, such as higher temperature endurance, radiation resistant, aseismatic performance, mechanical strength and machinability, and lower cost. Using the metal bobbin, coils with temperature index of 420℃ or above can be built and the goal to eliminate the cooling system on top of the reactor can be achieved.