Relationship between crosslink density and sol-gel contents for the hydroxyl terminated polybutadiene-isophorone diisocyanate polyurethane elastomer was investigated The crosslink density is directly proportional to functions of the sol-gel contents based on the reactive portion of the these stocks. The Scanlan, Flory-Miller-Macosko, Charlesby and French schemes were applied to evaluate the relationships between the crosslink density and the corresponding sol-gel contents of the present materials. The crosslink density in the gel polymer was found to be closely related to functional group equivalent weight, functionality of prepolymer, and the gel content of the maximum cured elastomer. Above analytic r?? lts indicated that the rubber elasticity behavior of the present material is very similar to that of French''s network materials formed from the reaction of functional groups on low molecular weight telechelic polymers with a crosslinking agent.