Traditional towed line arrays using omni-directional sensor suffer from the well known port-starboard ambiguity, because the direction of arrival is determined by conic angle. The operational method and structure of the sensor arrays method have been proposed to solve this problem. Recently, a lot of research relating to the acoustic vector sensor are studied. In this paper, we study port-starboard discrimination for roll of acoustic vector sensor array. With one omni-directional sensor and three orthogonally-placed directional sensors, an acoustic vector sensor is able to measure both the acoustic pressure and the three directional velocities at the point of the sensor. The wrong axis due to the roll at directional sensors can degrade performance of beamforming. We investigate port-starboard discrimination for roll of sensor array and confirm the validity of performance of beamforming with compensated the roll.