<正> The spatial distribution function and second moments of circular freely jointed chain are derived based on an analytical method. The circular Gauss chain

which is simple for long chains

is compared with the circular freely jointed chain

which is exact for short chains. It is shown that the Gauss chain model predicts a more compact configurational distribution than the exact freely jointed chain. The two chain models

however

become closer to each other when the chain length increases. It is found that the difference of the mean square radius of gyration calculated with these two chain models is a constant

independent of the chain length.