By using DSC, the behavior of second melting and nonisothermal crystallization of pure gel pure sol and sol — gel blend of radiation crosslinking HDPE was studied. We found that, because of the existence of sol, there is notable difference between pure gel and pure sol or sol — gel blend. Under the same dose, the melting point and crystallization temperature of pure sol and sol — gel blend are higher than that of pure gel. At the same time, we also found that the Avrami exponent of original PE、pure sol and sol — gel blend is the similar to each other and different to that of pure gel, which means that the procedure of nucleation and growth of these samples is the same and also different to that of pure gel.