Abstract: In this paper,a smart junction box for PV modules is designed.The junction box is just a MPPT controller with the modified PSO algorithm.In this paper,the hardware design and algorithm control in the intelligent junction box of PV module are introduced in detail,and the rationality of the hardware and the efficiency of the software are verified by experiments.The experiment results show that the intelligent junction box can handle the shadow occlusion problem,which also can increase the efficiency by more than 10%.