Valley filter is a promising device for producing valley polarized current in graphene-like two-dimensional honey-comb lattice materials.The relatively large spin-orbit coupling in silicene contributes to remarkable quantum spin Hall effect,which leads to distinctive valley-dependent transport properties compared with intrinsic graphene.In this paper,quantized conductance and valley polarization in silicene nanoconstrictions are theoretically investigated in quantum spin-Hall insulator phase.Nearly perfect valley filter effect is found by aligning the gate voltage in the central constriction region.However,the valley polarization plateaus are shifted with the increase of spin-orbit coupling strength,accompa-nied by smooth variation of polarization reversal.Our findings provide new strategies to control the valley polarization in valleytronic devices.