A harmless treatment technology for separation and recovery of oily sludge comprises the following steps: 1, conveying the oily sludge to a high solid content treatment device, carrying out preliminary screening on large granule impurities in the oily sludge, and conditioning the sludge; 2, conveying pre-conditioned oily sludge to a three-phase centrifuge, and separating oil, water and mud in the oily sludge; 3, conveying the obtained separated liquid to an oil-water separation device, and further carrying out oil and water separation; 4, inputting the obtained oil phase to an oil storage tank, and inputting water to an oily wastewater advanced treatment system; 5, conveying the obtained solid phase sludge transported to a thermal desorption device, and carrying out heating curing separation and condensation oil-water separation in a thermal desorption treatment process; and 6, conveying water output by the oil-water separation device and water output by the thermal desorption device to the oily wastewater advanced treatment system, and carrying out advanced oil-water separation. The method has the advantages of low cost oily sludge treatment cost, convenient maintenance and management, high efficiency and good stability.