A model is developed to investigate the effects of 3-dimensional shear flow on the stability of a crystal interface in the supercooled binary melt. The growth rate of the interface perturbation amplitude under shear flow is presented. It is found that the shear flow reduced the normal gradients of the perturbations of the temperature field and solute field, which can decrease therefore the growth rate of perturbation amplitude. The critical stability radius of the crystal interface increased with the shearing rate. The stability effect of shear flow decreased remarkably with increasing melt undercooling. (C) 2011 Elsevier B.V. All rights reserved.