The control rod drive mechanism (CRDM) is one of the key equipment related to reactor normal operation, safety and reliability. The CRDM structures often use magnetic jack type. The electromagnetic design is a core content in the CRDM design and key technology to ensure mechanism safe and steady operation. Based on the key technology research the ANSYS program and analysis method are verified, and the feasibility of electromagnetic field analysis with finite element is validated. According to the inputs of calculation manual for CRDM, the electromagnetic fields of lift, movable and tationary magnetic routes are computed. The electromagnetic field of CRDM integral magnetic route is analyzed. The three cases, which the current direction of lift magnetic route is uniform and opposite as the movable magnetic route's, and which the lift magnetic route is electrified alone, are computed.