We have simulated the end structures of perfect single-walled carbon nanotube at temperatures from 2000 K to 3500 K using tight binding molecular dynamics method. Our calculations suggest that the effect of temperature on the ends of the nanotubes is important. The two ends of a perfect single-walled carbon nanotube closes in turn at 3000 K and 3500 K within 15 ps. As the temperature increases, the two ends of a perfect single-walled carbon nanotube will close more quickly. Both processes of closing of two ends are accompanied by the lowing of the system energy. Moreover, the ends of armchair-type carbon nanotube close easier than those of zigzag carbon nanotube with the same diameter due to the lower strain energy of the former.