Plasmonic nanomaterials have wide applications in many fields, such as photocatalysis, solar cell, and new energy generation system. Among them, AgCl-Ag nanomaterials with excellent plasmonic property are getting more and more attention. In this work, AgCl@Ag core-shell nanocubes (AgCl@Ag CS-NCs) with highly uniform morphology and controlled composition have been successfully prepared by the partial reduction of AgCl nanocubes. The morphology, composition, and structure of AgCl@Ag CS-NCs have been investigated systematically. AgCl@Ag CS-NCs with the ratio of AgCl/Ag = 2.7:1 show the optimizational photocatalytic activity for the reduction of representative carcinogenic contaminant (Cr-VI), which is much higher than that of commercial P25 photocatalyst. The localized surface plasmon resonance and Schottky junction of AgCl@Ag CS-NCs contribute to the high photocatalytic activity for the Cr-VI photoreduction. After 5 times recyclable catalysis, the high photocatalytic activity of AgCl@Ag CS-NCs can still be maintained well, which demonstrates that AgCl@Ag CS-NCs possess excellent reusability and stability. The high activity and durability make AgCl@Ag CS-NCs to become a promising candidate for the environmental pollution purification under the sunlight irradiation condition.