This paper highlights the lubricating and film-forming behaviors of diketone and surface characteristics of tribopairs after the friction test. An ultralow friction coefficient of 0.007 is accomplished on steel surfaces with diketone. The existence of tribochemical adsorption films inside the wear track is directly measured and observed. Moreover, a well-developed conformal contact surface morphology is generated between two friction pairs, which can be helpful to the realization of ultralow friction on rough surfaces. In addition, the film thickness of diketone was detected using by relative optical interference intensity (ROII) under different rolling speeds. Present work reveals that diketone lubricant has a good lubricating performance on steel surfaces, and can be extended to applications with small loads.