AbstractThe properties of polyacrylamide for oil displacement are determined by the microstructure. Optimizing the method of studying the microstructure of polyacrylamide is convenient to screen out the oil displacement polymer with better performance in practice. In this paper, the effects of the degree of hydrolysis on the macroscopic viscosity and micromolecular morphology of polyacrylamide were investigated by using a new method of laser scanning fluorescence microscopy, atomic force microscopy, and cryo‐etching transmission electron microscopy. In the experiment, the influence of alkali content on the dynamic viscosity and micromorphology of the solution was eliminated by the innovative method of dialysis and alkali removal, which ensured the degree of hydrolysis as a single variable. The results show that the dynamic viscosity is less affected by the degree of hydrolysis macroscopically. With the increase of the degree of hydrolysis, the streamline structure of the molecule changed from coarse branched cluster to fluffy line. The chances of intermolecular entanglement are increased during the transformation process, which makes the microstructure characteristics agree with the results that the viscosity changes slightly with the degree of hydrolysis after alkali removal.