Exploiting highly efficient and stable photocatalysts for Cr(VI) reduction is of great importance. Herein, both homojunction and heterojunction are introduced into a novel QDs self-decorated Bi2MoO6 coupled with two-dimensional BCN (BCN-BMO(Q)) photocatalyst to achieve an enhanced performance of Cr(VI) reduction. Owing to the unique structure of the ternary system, electron-hole pairs are efficiently separated and transfer from the Bi2MoO6 QDs to Bi2MoO6 to BCN under visible-light excitation. Interestingly, 5% BCN-BMO(Q) shows stable and optimal performance for Cr(VI) photo-reduction activity within 20 min, which is almost 7.14, 2.28 and 1.66 times higher than that of BCN, BMO and BMO(Q) respectively under visible light irradiation. This work provides an alternative route to improve the photocatalytic activity of Bi2MoO6-based or some other nanocomposites.