In order to meet the requirements of on-line monitoring for 10kV high voltage switchgear, a design of data acquisition, processing and communication based on a multilayer distributed structure is proposed. This system is composed of data acquisition and communication unit, distributed monitoring unit and remote monitoring terminal, with Ethernet communication scheme to enhance transmission rate and interoperability. Advantages of ARM and FPGA in the on-line monitoring field are explained, and on this basis a dual-core embedded main control unit is designed. The Timing control of FPGA to receive multi-channel data and the hardware and software settings in ARM to send data by Ethernet are detailedly introduced. The Ethernet packets sent by ARM are received by the industrial personal computer, which is responsible for the man-machine interface and data storage. Experiment shows that several electrical and mechanical variables can be real-time monitored by this system. The system's stability and accuracy in data processing are also verified in the experiment.