To improve the low-elevation detection performance of ship-borne phased array radar， the low angle multi-path model， sea surface reflection model and elevation estimation model of phased array radar （PAR） are established. The relationship between low-elevation angle accuracy of ship-borne PAR and angle estimation method， radar frequency， beam direction， sea state and beam width is systematically analyzed through simulation. The results show that sum-sum angle estimation method， lower beam width by improved beam weight， higher beam direction of angle estimation sum beam， multi-frequency smoothing are benefit for low-elevation angle accuracy improvement. A low-elevation angle estimation method which takes advantage of all the factors above is proposed， which has achieved excellent real-world application results and significant engineering practical prospects.