[en] The design and implement of logical control and monitor system of the lower hybrid current drive (LHCD) system on HL-2A tokamak was present. The system was based on the SIEMENS S7-400 series PLC. The performance on anti-interference was increased by using the industrial ethernet network, optical fiber isolation, embedded controller technology. The interlocks, parameter setting and remote monitor were established. The lower hybrid wave was injected into HL-2A plasma with the logical control system. It shows the logical control system was successfully developed. (authors)