The modified Flory equation with combination of Cluff-Gladding-Pariser method provides useful information about cure state and some rubber structure for HNBR compounds with and without fillers. Determination of the Interaction Parameter for each compound only once gives the possibility to define the degree of cure state, compare the crosslink density or network for different rubbers and define the type of interaction between filler and polymer. It was shown that the rubber-filler interactions play a significant role in the network structure. An empirical correlation between V-r and M-c was derived which makes it easier to find the molecular weight between crosslinks without determination of Interaction Parameter. The influence of unsaturation on rubber properties with and without fillers has been also evaluated.