The Internal Combustion Engine Power Plant and Flywheel Battery were the two primarily compositive units of the Internal Combustion Engine Power Plant --Rotary UPS, among them the Internal Combustion Engine Power Plant ensured the continuous power supply to the load after the breaking of the mains supply, the Flywheel Battery ensured the uninterruptible continuous power supply to the load when mains supply switched to the Internal Combustion Engine Power Plant, so the paper started with the two units, Introduced the control system structure and principle, and focused on discussing the method of achieving the Internal Combustion Engine Power Plant --Rotary UPS telecommunication by Ethernet. The method had been applied in correlative production. The practice showed that it was convenient for usage and high reliability.