Globally, oleaginous plants (OP) production has recorded significant growth, due to their large applications in biofuels industry or vegetable oil production for cosmetics, pharmaceuticals, dyes or industrial applications. The oleaginous plants chosen for this study are Carthamus tinctorius L., Silybum marianum L., Linum usitatissimum L. and Helianthus annus L., which are renowned for their high oil and fiber content. In order to optimize the methods for determining the total fiber content and the global digestion process of the non-cellulosic components of these oil plants, experimental design statistical techniques have been developed using statistical models such as multiple regression with variance analysis applied using the ANOVA test. The present study aims at a comparative statistical analysis on the identification and optimization of fiber extraction methods in the four OP chosen. Moreover, the study allowed the identification of the optimal values of the experimental parameters and the 'desirability' function to be used to evaluate the final responses. In conclusion, this study helps us to found a favorable way of obtaining fibers using modern extraction methods.