The copolymefization of aerylamide (AM) and sodium 2-acrylamido-2-methyl-propane-sulfonate (NaAMPS) was carried in aqueous solution

and a series of copolymer P(AM-co-NaAMPS) with varied composition were prepared The structure and composition of the copolymers were characterized by FTIR spectroscopy and element analysis．The viscosities of the copolymers were determined using an Ubbelohde viscometer

and the intrinsic viscosities by which molecular weight can be calculated were determined with the method of extiapolation to zeio concentration At the same time the Huggins constants by which the interaction between polymer and solvent can be displayed were also obtained．The apparent viscosities of aqueous solutions and brine of the copolymers were measured using a low shear rotational viscometer．Thermal stability experiments were carried out formeasufing the maintaining ratios of viscosity at high temperatures．In this work

the relationships between the structare and composition and the properties of the copolymers P(AM-co-NaAMPS) were studied．The experimental result shows that the properties of the copolymers P(AM-co-NaAMPS) depend strongly on their structure and compositions

and incorporation of the NaAMPS segments in polymer backbone of PAM results in excellent properties of the copolymers

such as better solubility

better thickening ability

improved resistance to temperature and improved salt tolerance due to the strong anionic property of sulfonate groups and sterlc hindrance of great side groups．These properties are significant in enhanced oil recovery．The molecular weisat of the copolymers is influenced by their composition and the polymerization process At the same time

the molecular weight is also an important parameter influencing the properties of the eopolymer．The experimental results indicate that the properties of the copolymer vary regularly with its structure and composition．