OBJECTIVE： To study the percutaneous properties of Man-PEI25k nanocomplex under the treatment of microneedles. METHODS： Using fluorescent dye water-soluble carboxyl CdSe/ZnS quantum dot （QD） as model drug， Man-PEI25k/QD and Man-PEI25k/QD nanocomplex with different grafting rates （1 ∶ 3， 1 ∶ 6） were formed through electrostatic adherence with PEI25k and Man-PEI25k. The distribution of QD in the active epidermal layer and dermis of skin were observed by confocal microscopy after the treatment of microneedles， using free QD as control. The accumulative retention amounts of QD in the active epidermal layer and dermis of skin were determined by fluorescence spectrophotometer after PEI25k/QD and Man-PEI25k/QD nanocomplex treated with microneedles. RESULTS： The amounts of Man-PEI25k/QD nanocomplex in active epidermal layer and dermis were significantly higher than that of PEI25k/QD nanocomplex under the treatment of microneedles in vivo； the amounts of Man-PEI25k/QD （1 ∶ 6） nanocomplex in active epidermal layer and dermis of skin were significantly higher than that of Man-PEI25k/QD （1 ∶ 3） nanocomplex. In in vitro transdermal diffusion experiments， microneedles could increase the retention amounts of nanocomplex in active epidermal layer and dermis of skin significantly. The retention amounts of Man-PEI25k/QD nanocomplex in active epidermal layer were increased by 2 times of that of PEI25k/QD under the treatment of microneedles after 48 h； at the same time， in the dermis that was increased by 1.5 times， with statistical significance （P＜0.01）. CONCLUSIONS： Microneedles can improve the percutaneous properties of Man-PEI25k nanocomplex in active epidermal layer.