The formation test tool of Schlumberger includes RFT andMDT. The application of conventional RFT is limited by itsfunctional defects in practice. The new generation MDT hasgained satisfied geological effect in oil field due to its advantages , such as the advanced capability of assemblage , fluid performance monitoring , the sampling through precise pressure
management , and shown a good prospect . In this paper , thework principle and interpretation method of MDT tool are comprehensively described , and its case application in Sichuan isspecifically analyzed. It is a good reference for applying MDT data to interpret .