The influence of initial entanglement on entanglement evolution under phase damping channel in noninertial frame is investigated. Compared with the scenario of amplitude damping channel, when the state parameter α has different values with the same intial entanglement, the evolution curves are identical. When the Unruh single particle state has right and left components, there is more serious quantum decoherence than the case where the Unruh single particle state has only right component with the sudden death of entanglement taking place early, and the time of sudden death of entanglement is independent of initial entanglement.