The elliptic flow v2,for π±,K±,p and (P) in Au+-Au collisions at center-of-mass energies s√SNN =7.7,11.5,14.5 and 19.6 GeV,is analyzed using a multiphase transport model A significant difference in the v2 values for p and (P) is observed,and the values of v2 splitting are larger compared with π+ and π-,K+ and K-.The difference increases with decreasing the center-of-mass energy.The effect of the quark coalescence mechanism in a multi-phase transport model to the value of elliptic difference △v2 between p and (P) has been discussed.The simulation of Au+Au collisions at 14.5 GeV shows that the effect of hadron cascade to △v2 is not obvious,and a larger parton-scattering cross section can lead to a larger △v2.