Objective To study port-externalized tissue expansion technique and to provide a safe,simple and effective skin tissue expansion for extensive skin lesion reconstruction.Methods A lot of 247 patients with extensive skin lesion were chosen for the study.400-1000 ml tissue expanders were used for overexpansion and repeated expansion.Expanders were inserted into subcutaneous pockets through mini-invasive incisions and intermittent injection was carried out 4 days after first stage operation.After expansion finished,expanded skin flaps were transplanted for skin lesion reconstruction.During inflation period,complications and expander failures were observed.Results In 741 expanders of 247 patients,complication rate was 16.5 ％ with total 122 cases of complications.Expansion success rate was 98.9 ％ with 8 expander failures.Expanders were inflated successfully between 64-113 days,with average 92.7 days.The inflated saline volume was 2.38 times of marked expander capacity.In this group of 733 expanded skin flaps,721 flaps were well survived with 98.4％ success rate.276 expanded flaps of 116 patients were followed up for one to five years post-operation.The width of incision scar was between 0.3-1.2 mm.Conclusions The port-externalized overexpansion with giant expanders is a safe,simple and feasible technique,which is worthy of further clinical application.