A new design scheme of on-line monitoring system based on internet for line arrester was proposed to solve the problems that current line arrester on-line monitoring system was single function, poor anti-jamming ability and inaccurate test data. STM32 was used as the control center, the passive wireless surface acoustic wave sensor was used to measure the temperature of the arrester, Rogowski coil was used to acquire lightning current signals, the lightning current signal was processed by the FPGA and op amp, 4G communication module was used as wireless transmission module, field data was transmitted to a remote expert diagnostic system through the Internet, finally, smart arrester online monitoring function is achieved. The experimental results show that line arrester"s real-time operating status was monitored remotely.