Abstract: The article introduces the work principle of HGC-1 Crude Oil Custody Transfer System, which consists of HGC-19 water content sensor, SCS-30 electric platform scale, computer system and water cut automatic metering monitoring software. This system can effectively solve the questions in inaccuracy water cut ratio data of road tank from human metering error, tired job of staffs and disputation between the trading parties on the oil volume. The application of this system shows that it has a high economic feasibility in oil unloading of oilfield and is the technical fundamentals for the sustained and effective development of oilfield.