The conformational variation of a polymer chain terminally attached to a surface at different temperatures was studied by using Monte Carlo and simulated annealing methods．The model polymer chain was a self-avoiding walk with non-bonded nearest-neighbor interactions on a simple cubic lattice It was shown in results of computer simulations that in dilute solutions the tail chain

like the free chain

undergoes the phase transition from a loose coll to a compact globule when the temperature decreases．The mean square end-to-end distances and their components

as well as the mean square radius of gyration and their distributions were calculated at different temperatures Due to the existence of the surface

the curves expressing the chain size versus temperature for the tail chain were slightly lower than those for the free chain．It was also found that the effect of the surface on the shape of the polymer chain was obvious at high temperature

and the perpendicular component of mean square end-to-end distance was significantly larger than the parallel component However

below the θ temperature

especially after the full collapse of the polymer chain

the effect of the surface on the chain shape becomes very small．