The embodiment of the invention provides an underground ropeless testing system for an oil well. The underground ropeless testing system comprises a wireless tester and a self-generating set, wherein the wireless tester comprises an underground tester, a sensor group, an underground test end circuit and an electromagnetic wave transmitter, wherein the sensor group is arranged on the underground tester, the underground test end circuit is connected with the sensor group and used for amplifying and converting production data collected by the sensor group; and the electromagnetic wave transmitter is connected with the underground test end circuit, and used for transmitting the processed production data to a ground processing system. The sensor group, the underground test end circuit and the electromagnetic wave transmitter are arranged on the underground tester, thus ropeless directly-reading test of underground production data of a pumping machine is realized, and the problems of high cost and large construction difficulty existing in the prior art are solved.