Abstract: Possibility of non -Gaussian short chains and interlooping chains formed in gel-network, and their influence on swelling characteristics of gels are discussed on the basis of Florys physical -entanglement model. A new molecular thermodynamic theory for non -ionic gels basec on a lattic - fluid model and an elastic model is introduced in which the elastic contribution by the non -Gaussian short chains and interlooping chains is included. The theory can be used to describe various phase behaviors for temperature -sensitive gels. Satisfactory results art obtaind in the correlation of practical swelling equilibria.