Two sodium alginate (SA) was selected to analyze the materials for guiding the spinning. Employing the Ubbelohde viscometer, the viscosity-average molecular weight of these two different sodium alginate (SA) were determined firstly, which was 130 436 ~ 204 070 Da and 541 636 ~ 569 846 Da. Besides, the solutions were determined or derived in the field of rheology through rotating cylinder viscometer, and the results show that there exists the characteristic of shear thinning, which is consistent with the primary character of Bingham liquid. Then the freeze-dried sponge of SA solutions were analyzed by infrared spectrum, and the proportion of R-D-mannuronate (M) and â-L-guluronate(G) in the chains of SA were calculated through the spectrum, that′s 1.31(A) and 1.86(B) . Finally, the mechanical properties of SA films were figured, and the results show that the M/G ratio of the materials affected the mechanical properties of SA and probably make SA represent two different specialities of 〞infirm and brickle〞or 〞strong and brickle〞.