Oil-water two-phase flow commonly exists in many industries. The accurate measurement of flow velocity is beneficial for safety operation and economic efficiency. A combination of a pulse-wave ultrasonic Doppler (PWUD) sensor and a conductance/capacitance (CCC) sensor is proposed for flow velocity measurement in dispersed oil-water two-phase flow. The PWUD sensor estimates dispersed phase velocity, and the CCC sensor provides phase fraction. The overall superficial flow velocity (J) and individual flow velocities are estimated by combining the outputs of the two sensors. The dual-modality sensing system was designed and experimentally verified on a horizontal multiphase flow loop. Ignoring the slippage between two phases, the J is estimated with an average relative error (ARE) of 5.58%, water superficial velocity with 6.42%, and oil superficial velocity with 6.91%. To further improve the measurement accuracy, slip velocity-based measurement model is presented by introducing the drift-flux model. The distribution parameter of this model is derived from theoretical analysis. The correlation between relative velocity and J is analyzed by the force analysis of dispersed phase in water/oil-continuous flow theoretically and experimentally. The results demonstrate that the proposed model estimates the J with an ARE of 2.21%, water superficial velocity with 3.56%, and oil superficial velocity with 3.80%. Besides, ARE of different flow patterns shows a uniform distribution. The slip velocity-based measurement model has an advantage of less error in overall superficial flow velocity estimation, reduced by 60% compared with that of the nonslip velocity-based measurement model.