Based on the model of random walk on the simple cubic lattice,the distribution function of conformation of a polymer chain in an interfacial layer was deduced.If the model chain was consisted of N segments, it was possible to form both the tail chain, when the terminal segments were adsorbed at the interface, and the adsorbed chain with the non\|terminal group.The conformational number Ω tail of a tail chain is equal to Ω free /(6π N ) 1/2 ,where Ω free is the conformational number of a chain in free state and equals to 6 N for this random walk model. It was found from theoretical analysis that, for the set of a chain attached non\|terminally to the interface, the total conformational number Ω tot is equal to Ω free /6.As an result,the average conformational number m for the chain attached non\|terminally to the interface is Ω \{free\}/6 N .In the case of short chain,for instance N is equal to about 10,the conformational number Ω \{tail\} of tail chain is even larger than the total number Ω \{tot\}. In the limitation of long chain, however, the conformational number Ω \{tail\} for tail chain is nuch large than m,but smaller than Ω \{tot\}. The conclusion is that the distribution function of conformation for chains in the interfacial layer is not uniform,but has a special distribution form described in this paper.
