The effect of initial longitudinal velocity of the tunnelled electron on the non-sequential double ionization (NSDI)process in an elliptically polarized laser field is studied by a semiclassical model.We find that the non-zero initial longitudinal velocity has a suppressing effect on single-retu collision (SRC) events in the double ionization process,more specifically,it results in an obvious reduction in the center part of the correlation momentum distributions in the direction of the major polarization axis (z axis) and makes the distribution of single-retu collision in the minor polarization axis (x axis) become narrower.