An effective mode selection is important for the multi-core photonic crystal fiber(PCF)to obtain good output.Talbot cavity is popular to lock the in-phase mode,but few satisfactory experimental results have been reported.In this paper,a dual-Talbot cavity with reflected mirrors on each side of PCF is designed to lock the in-phase mode.The design gains the advantage of in-phase mode against out-of-phase mode.What’s more,it can weaken the influence brought by the imperfect end facet of the fiber.The corresponding theoretical analyses and the experiment are taken.The experimental results suggest that the dual-Talbot cavity improves the capacity of mode selection. An effective mode selection is important for the multi-core photonic crystal fiber (PCF) to obtain good output. Balbot cavity is popular to lock the in-phase mode, but few lasts experimental results have been reported. This paper, a dual- Talbot cavity with reflected mirrors on each side of PCF is designed to lock the in-phase mode. The design gains the advantage of in-phase mode against out-of-phase mode. What’s more, it can weaken the influence caused by the imperfect end facet of the fiber.The corresponding theoretical analyzes and the experiment are taken. the experimental results suggest that the dual-Talbot cavity improves the capacity of mode selection.