This study reports the shear-responsive gelation of an aqueous solution of polyacrylic acid-co-polyacrylamide (PAA-co-PAM). Microstructure characterization and molecular dynamics simulation reveal that the shear action results in the ordering of the polymer chains, thus increasing the strength of hydrogen bonds between chains and forming gel. Friction tests reveal that the PAA-co-PAM aqueous solution effectively reduces the friction and wear of Si3N4 friction pairs via the in situ formation of a colloidal lubrication film which could cooperate with the silica gel layer generated on the Si3N4 surface. Owing to the shear gelation characteristics of the PAA-co-PAM aqueous solution, the hydrogel lubrication film could be continuously formed under shear action, thus overcoming the insufficient lifetimes of existing hydrogel lubricants.