Positive Q-value neutron transfer mediated sub-barrier fusion reactions axe studied with an empirical coupled channels model,which takes into account neutron reaarangement related only to the dynamical matching condition with no free parameters.Fusion cross sections of collision systems 32S+90,94,96Zr are calculated and analyzed.Logarithmic residual enhancement (LRE) is proposed to evaluate the discrepancy between calculated results and experimental data.The experimental data can be described well with this model for the first time as a whole,while the LRE analysis shows that there are still theoretical systematic deviations.