Abstract: The phase modulator is important in laser phased array. The arrayed phase modulator based on optical waveguide is proposed. The index profile in annealed proton-exchanged(APE) LiNb03 waveguide is studied theoretically and simulated by beam propagation method(BPM). High uniformity of output power is gained numerically by optimized design of cascaded Y-branch. The structure with long electrodes is designed to obtain low half-wave voltage. The 1 × 4 arrayed phase modulator is finally fabricated using APE technology. The optical and electrical properties are tested. The insertion loss is 6. 83 dB,the uniformity of output power is 0. 23 dB,and the voltages are 2.1,3.4,2.0,and 2.1 V,respectively,which indicates that the arrayed phase modulator can satisfy the theory and expectation well.