Abstract: The paper describes main function design criteria and requirement, main tech-nical parameters of the control rod drive mechanism prototype for the FFR atfirst. Then describes in detail the structure and parameters of eight basiccomponents, i.e. the main drive system, the fast release system, thedamping system,the gripper system, the seal system, position indication system, the spring compensationdevice and the mechanical lock device. Finally, the structure features and thedesign backgroundes are described.