The dynamic laser scattering (DLS) method was used to study the structure of polyacrylamide (PAAm) gel

whose crosslinker ratio ranged from 1.6％ to 4.8％ while the total monomer concentration kept constant at 2.66％. The data analysis method of DLS and the meaning of the analysis were studied intensively．The results of DLS experiments showed that there were two different phases with distinguishing dynamic correlation length (LC) in PAAm gels．Analysis based on the gelation mechanism revealed that the existence of the two kinds of phases in PAAm gels Was mainly due to the poor solubility of the crosslinker．The phase with LC about 85 nm was polymer rich phase formed by the microgel spheres in the pregel solution while the other with LC within 10～20 nm was polymer poor phase formed by the crosslinking area between those spheres．So the LC of polymer rich phase was its size and that of polymer poor phase was the mesh size of PAAm gels．The irregular distribution of the two kinds of phases would lead to the inhomogeneity

which increased significantly with crosslinker ratio because the increase of crosslinker ratio would increase the fraction of polymer rich phase and decrease the fraction of polymer poor phase．In addition．the points with same scattered intensity had same fraction of polymer poor phase and polymer rich phase with the same LC

which meant that the structure of the points with same scattered intensity were similar．