Abstract: Introduced in this paper is the static pressure, program controlled measurement system for tanks with internal floating roof, which is made up of directly drawing pressure unit, capacitive based differential pressure transmitter with high precision, current based integrated temperature sensor, cognate circuits, multipath and high resolution PC bus interfcae card and a master computer of IBM-PC 386. Supported by a UCDOS 3. 1 Chinese platform, the system is developed by using C language. A calculating method on program control metering directly drawing pressure for tanks with internal floating roof including non-metering area is established, and the static pressure of the oil stored can be rnetered with the capacity based differential pressure transmitter(1151 DP 5E intrinsic safety model) by the unit installed at tank bottom. The commercial mass of oil stored can be computed automatically based on the calculating program mentioned above written by the C language, and the parameters of measured density, oil level and volume can also be determined by inputting its standard density and mean temperature measured. This method has such advantages as high accuracy, good stability, multi-functions and ease maintain over that of hand-dipping, servo level gauge and radar level gauge.