This article deals with the calculation of the elastic properties of cellulose based natural fibers by using two different types of idealization and assumptions. One model (model A) bases on antisymmertrical laminated structure, while the second one (model B) bases on a thick laminated composite tube model. Model B is able to take into account the elliptic geometry, the hollow based structure of the cross section of the fiber cell. The calculated relationships between spiral angle and modulus in fiber axis by model A fits successful experimental data for holocellulose fibers which were published elsewhere. In general, modulus in fiber axis decreases with increasing spiral angle as well as the degree of anisotropy, while shear modulus reaches a maximum for a spiral angle of 45 degrees. Fiber cell modulus increases linear with increasing cellulose content for both, the calculated (model A) and measured values. The correlation between experimental data and calculation ones was not as high as in the case of modulus versus spiral angle. The discrepancy between model A and a more real cross section is calculated (model B) with roughly 30%.