In order to obtain the transient lubricating film thickness of slider bearings, a conformal contact film thickness measurement system has been developed based on dichromatic interferometry. Firstly, the basic setup of the slider bearing tester is introduced together with its working principle. The method and the resolution of dichromatic equivalent wavelength for relative large film thickness measurement are also thoroughly analyzed. Then, a plain and feasible approach is proposed for transient film thickness measurement, whereby fringe order of equivalent wavelength is conducted through dark characterized fringes and the corresponding fringe order of red or green monochromatic light is identified with modulated intensity signal to infer the film thickness. Theoretical and experimental results indicate that the well built system can be used to measure transient lubricating film thickness. The resolution of the dichromatic interference method is 0.6 nm with a measurement range from 10 nm to 5.5 μm, and the precision is 22 nm.