Abstract: This paper is based on the finite element simulation method for Z-pin reinforced T-joints about pull-off load. After the analysis on the test results of specimens with two different skin thicknesses (7.2 mm and 4.0 mm respectively), influence of skin thickness on the reinforcing effect of Z-pin was studied. Results show that the reinforcing effect of Z-pin increases as the thickness of skin decreases. When the skin is thicker than 5 mm, Z-pin cannot increase the maximum load-carrying capacity of structure any more, while Z-pin can still enhance the load-carrying performance after the first peak load, thus make the T-joints remain high load-carrying capacity under big load displacement. Whatever the thickness of skin is, load plateaus of Z-pin reinforced T-joints after first peak load are almost the same and the level of load plateau decreases as the thickness of skin increases.