This paper is concerned with the theory on electron beam curing of polyether acrylic isocyanate oligomers, which belong to the terminal acrylic type with the structure expressed as follows:,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648215&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648224&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648223&type=,As each double bond is a bifunctional group, these oligomers can be considered as the A,a, type molecule in the theoretical treatment. In the present work, the respective relationships among P,A, P,A(S), P,A(g), and S,A, were derived, these parameters are the total reacted extent of group A, the reacted extent of group A in sol, the reacted extent of group A in gel and sol fraction respectively. when S,A,→1, the critical values ofP,A, P,A(S), and P,A(g), are given with following formulae.,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648225&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648227&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648226&type=,Hence, the regularity about the curing process can be described as follows.,Before gel point (S,A,=1), value of P,A, or P,A(S), increases successively since P,A,=P,A(S),and P,A(g),=0;,At gel point (S,A,=1):,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648228&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648230&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648229&type=,After gel point (0,<,S,A,<,1): sol and gel coexist,P,A(g),>,P,A,>,P,A(s), and P,A, and P,A(g), increase monotonously but P,A(S), decreases.,Without sol in system S,A,=0;,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648218&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648222&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648219&type=,The height of the absorption plak in oligomer was measured from I. R. spectra at different total dose. The disappearance rate of double bond can be characterized with the rate of the height reduction, which is approximately equal to the P,A, value calculated from the equation of P,A, vs. S,A,.