The invention discloses a nuclear power plant personnel gate transmission system which comprises a middle transmission box provided with a containing space. Multiple layers of transmission assembliesare movably arranged in the containing space and detachably connected with the middle transmission box. Gear transmission is achieved between the transmission assemblies. The multiple layers of transmission assemblies are used for providing drive force. Pressure balance and a sealing door mechanism are driven according to the drive force, and the sealing door mechanism is opened through a mechanical interlocking manner. According to the system, after the transmission assemblies are integrated to the middle transmission box, a box body is designed in a modularized manner, installing of the middle transmission box and the transmission assemblies are decoupled, after a personnel gate is installed, when operation is needed, the middle transmission box is installed, site installing of a power station and the maintenance requirement during the debugging and maintaining period are avoided, and equipment in the box body is convenient to maintain and replace.