The conformational distributions of a model polymer tail chain was deduced based on the diamond lattice walk confined in the half space by means of the reflection principle.The relationship of the available conformational number C1(N) with the chain length N and the distribution function of end to end distance were obtained for this model tail chain.In the case of 4 choices diamond lattice walk

it was found that C1(N)/4N is proportional directly to N -1/2 .The component of the mean square end-to-end distance normal to the wall for the model tail extends to two times in comparison with the parallel components which is same as the components for the corresponding free chain.These analytical results were confirmed in computer experiments including the exact enumeration and Monte Carlo simulation.