Abstract: When testing operation is performed on the HTHP wells in Western South China Sea, a series of problems occur. For example, the flowing phase state of formation fluids is complex, the wellbore safety cannot be guaranteed easily for the testing string is under the effect of multiple loads, hydrate tends to form in the situation of high pressure and low temperature, sand production is serious, the testing fluid is highly required in high temperature stability, the space of offshore platform is limited, personnel and equipments are suffered from high safety risk, and so on. To deal with these problems, a set of offshore HTHP testing technologies are developed after years’ research and practice, such as offshore HTHP testing safety control system model, testing string safety analysis technology, wellbore safety evaluation technology, hydrate prediction and control technology, sanding prediction and control technology, surface process design optimization technology, and high-temperature testing fluid technology. They are well applied in field. Based on current situations and subsequent exploration demand in the petroleum industry, HTHP well testing will be developed from the aspects of the construction of offshore oil and gas testing information decision platform, the intelligentization of testing equipments and deepwater HTHP testing technology.