From the kinetic equation of gel formation obtained by this study, the mechanism of gel formation may be interpreted clearly as follows:,(1) When the degree of crosslinking q,<,q,g, the system is sol and the crosslinking reaction is only carried out between the sol molecules. (q,g, is the gel point).,(2) when q=q,g, there exists a beginning point where the gel is coexisted with the sol, and the system is still sol, and the crosslinking reaction is still carried out between the sol molecules.,(3) When q,>,q,g, the crosslinking reaction exceeds the gel point and the gel is coexisted with the sol. The kinetic equation shows clearly that the transformation from sol into gel is caused by crosslinking reaction of the uncrosslinked chain units between the sol and gel molecules. As a result the sol molecules are transformed into the gel molecules gradually, and the sol fraction is reduced. When the chain units ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648872&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648874&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648873&type=, in sol are crosslinked with gel, the sol fraction in the system are reduced ds (where ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648875&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648884&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648876&type=, is a function of the radiation dose and S is sol fraction.),The degree of crasslinking per unit dose (q,0,) is reduced function of dose (R), so its value for every irradiation dose may be calculated by following equation,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648879&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648881&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648885&type=,therefore, the relationship between q,0, and R will be known. After knowing the correlation between ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648882&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648890&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648889&type=, vs R and q,0, vs R, the distribution of gel and sol in the process of radiation crosslinking can be discussed according to the equation ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648900&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648893&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648901&type=, dR as well.