The utility model relates to an underground oil/water interface acquisition detector controlled by a portable computer. A notebook computer is connected with a USB (universal serial bus) 8-circuit relay output module and a USB 8-circuit analog signal input module; a USB 8-circuit relay output module, a -9V low voltage detection power supply and a -18V high-voltage detection power supply form a loop; one end of the USB 8-circuit analog signal input module is connected with a relay, and the other end is connected with a detection sensor through a combination cable; the combination cable consists of two sets of composite cables; each set of composite cables are formed by twisting 3 single-core armored cables; the detection sensor is long semicylinder-shaped and fixedly installed at the outer side of an intermediate pipe corresponding to the detection depth of the sensor; one single-core armored cable core is connected at the parallel connection end of a constant current source circuit of each detection sensor; and the other end of the constant current source circuit of each detection sensor is installed at the bottom part of a contact of the detection sensor. When the detector is adopted, the accurate measurement of the oil/water interface can be realized, and the error caused by the pollution can be corrected.