Flow computer(date logger) is mainly used to trading discipline between supplier and customer in regional central heating, and calculating steam and high precision flow measurement. It is a full functional secondary instrument based on 32-bit ARM micro-processor, high speed AD and large-capacity storage, the instrument has fully adopted surface mount technology. It has good EMC ability and high reliability because of heavy protection and isolation in design. It is embedded RTOS, USB host, and high density Flash memory, which could record 720-day length sampling data. It can automatically identify saturated steam and super heated steam and also be used for process monitoring and volume control of steam heat. History data recorded in instrument can be copied to USB disk at any time and analyzed by DTM software on PC. The instrument may be used together with vary flow sensors such as orifice plate, V-cone, vortex flow meter and so on. Besides, it also features good performance in anti-theft and power failure protection.