A new model of quantum ring with multiple arms whose middle arm is curved was proposed in this article.This is an unequal arm quantum ring with a shortest upper arm and a longest lower arm.The results indicate that the persistent spin current shows nonperiodic vibration with the size of the semiconductor ring increasing when the total magnetic flux is zero.And it is related to the electrodes’ magnetic moment direction as well as the tunneling electrons’ spin orientation. The average persistent spin current in the lower arm is minimum on account of its longest length. When the AB magnetic flux strengthens, the persistent spin current in each arm generates periodic oscillation and shows mutual restriction.The difference in each arm is related to the arm length and the magnetic flux distribution. Furthermore,the Rashba spin-orbit interaction affects the phase and the phase difference of the persistent spin current. Our results also imply that the persistent spin currents which the two kind of wave functions correspond to are separated under definite conditions.