Sub parsec massive binary black holes are hard to be detected due to the low space resolution. We demonstrate that we can probe the binary black holes via analyzing the light curves of microlensed quasars. We create a set of artificial light curves of microlensed binary quasars in multi-band and use single accretion disk model to analyze these light curves. Given the estimate of the physical parameters including the size of accretion disk, the effective source velocity and the stellar mass fraction of the lens, we found that the binary system have a quite different behavior with the single system. The size and temperature profile of the system is flatter than the standard thin accretion disk model.