Four micro-holes were fabricated on the tool-chip contact area of the cemented carbide (WC+14%TiC+6%Co) tool face. MoS2 solid lubricants were embedded into the micro-holes to form self-lubricated tool (SLT-1). Dry machining tests on hardened steel were carried out with the SLT-1 self-lubricated tool, the SLT-2 tool with four micro-holes on the rake face embedded without solid lubricants and the SLT-3 conventional tool. The variation of cutting forces with cutting speed were tested by the Kistler force tester. The result shows that the three cutting force components of SLT-1 self-lubricated tool decreased obviously. They went down by 25-35% in comparison with those of the SLT-3 tool. And the three force components of SLT-2 tool decreased about 10-14% compared with those of the SLT-3 tool. Through the analysis of cutting force distribution theory and test results, the mechanism of cutting forces decrease was considered to be forming a self-lubricating film on the rake face which decreases the shear stress and the reduction of contact length between the chip and the tool.