Abstract: In this paper,we used the original carbon nanotubes (CNT) and the single-vacancy (SV) defects and Stone-Wales (SW) defects as the supports to study the adsorption behavior of Pt atom on the inner and outer surfaces of carbon nanotubes.The most stable adsorption structures inside and outside the carbon nanotubes have been found by calculating the adsorption energy and the charge,analyzing the front molecular orbital and the density of states etc.Furthermore,we analyze the influence of the defect on carbon nanotubes and on stability of Pt@carbon nanotubes.The calculated results show that the internal adsorption structure of the CNT is more stable than the external adsorption structure.The outer side adsorption on the defective carbon nanotubes is more favorable to the adsorption of Pt than the inside,and the presence of defects make the adsorption structure more stable than the CNT,and the structure with SV defects as the supports has the best fixation to Pt.Therefore,we can improve the stability and durability of the Pt catalyst by introducing the SV defect structure into the carbon nanotubes ,it can not only improving the stability of the carbon nanotube carrier but also improving the efficiency of the Pt catalyst.