In this paper,a graphene-on-silicon waveguide photodetector using a n all-pass microring is proposed.Structural parameters for the graphene-silicon m icroring resonator are optimized to satisfy the critical coupling condition and enhance the interaction of graphene and light.The designed graphene-on-silico n waveguide photodetectors are experimentally demonstrated by using a series of pr ocesses such as electron-beam lithography,inductively coupled plasma etching, g raphene transfer,and electron beam evaporation.Experimental results show that the the best responsivity of the fabricated photodetector is 12.5μA/W when the bias voltage is －0.1V.