Measuring　the　half-wave　voltage　with　high　accuracy　and　a　simple　setup　is　an　important　issue　for　the　applications　of　the　electro-optical　phase　modulator.　A　new　method　was　proposed　which　was　based　on　the　principal　of　beam　steering　in　the　laser　phased　array.　The　relationship　between　the　offset　of　central　beam　in　far　field　and　the　half-wave　voltage　was　formulated　by　theoretical　analysis.　The　setup　of　the　1×2　all-fiber　laser　phased　array　system　was　built　and　the　half-wave　voltage　of　the　LiNbO3　waveguide　phase　modulator　was　measured.　Several　far-field　intensity　distributions　with　different　loading　voltages　were　recorded　and　the　measuring　error　was　decreased　by　taking　average　of　the　multiple　results.　What＇s　more,　the　curve　of　phase　modulation　characteristic　was　obtained　according　to　the　multiple　far-field　intensity　distributions.　The　experimental　results　show　that　the　proposed　method　is　simple　with　high　accuracy　and　has　important　applications　in　engineering.　Meanwhile,　the　phase　modulation　linearity　can　be　analyzed.　©,　2015,　Chinese　Society　of　Astronautics.　All　right　reserved.