Abstract: This paper introduces the geologic features of Qian 12 unit, the principles of earth hydrochemistry temperature and pressure measuring technology, and presents the tetn-perature and pressure variations during fifth steam soaking in wells 63-447, 65-447, 64-48 and 66-48 in Qian 12 unit. Comparing with the measuring results obtained from TP-9ooo four-parameter measuring device, it indicates:the earth hydrochemistry temperature and pressure measuring technology can provide relatively accurate production behavior pa-rameters(for example, the temperature, pressure and so on of the reservoir during steam soaking), can realize measurement without shutting in, without pulling and dropping tubing strings, and can provide theoretical basis accurately and in time for the efficient development of an oil field.