Relating to the technical field of harmless treatment of petroleum exploitation sludge, the invention provides a harmless reinjection treatment method for petroleum exploitation sludge. By means of a pump station composed of several hydraulic injection pumps in parallel connection, the sludge generated in petroleum exploitation is sent to an abandoned layer of an oil field. The method provided in the invention employs the hydraulic injection pumps with long stroke, low stroke frequency and high pressure to inject the sludge into the abandoned layer of the oil field, therefore, the treatment problem of oilfield exploitation sludge is solved, and simultaneously the sludge is returned to underground, thus realizing recycling of petroleum resources in the sludge, enhancing the petroleum recovery rate of the oil field, and changing the waste petroleum exploitation sludge into things of value.