In context of global change, biodiversity loss poses a serious problem in the Mediterranean basin. In Algeria, degradation problems (logging, deforestation, bush fires and agriculture) affect vegetation. Knowledge of vegetation characteristics is necessary to manage disturbed areas. That is why this study focused on demographic structure of main species of Ouled Bechih forest (Quercus canariensis and Quercus suber). On eight plots representing this forest of 900 m2, chosen at random, dendrometric and phytosociological parameters are collected. Results obtained reveal a total specific richness of 41 species. Principal families are Asteraceae (21.95%) and Fabaceae (7.32%). Average woody density is 154 individuals/ha with an average basal area of 27.33 m2/ha. Variance analysis shows that there is a high significant difference between the dendrometric parameters (p<0.001). Diameter and height structures are consistent with Weibull distribution. These structures indicate that trees are moderately stable with predominance of large diameter individuals. Results obtained will allow monitoring the vegetation dynamics and will help foresters to put in place a management plan to preserve this forest.