Crude oil is a complex colloidal system composed of various hydrocarbons and non hydrocarbon compounds containing heteroatoms. Crude oil with high content of n-alkanes has a high pour point. When the temperature of the crude oil drops to a certain extent, tiny wax crystals will precipitate, and the wax crystals will combine to form a three-dimensional network structure, encapsulating the liquid components of the crude oil and causing it to lose its fluidity. This study synthesized polyamides from fatty acids and polyamines, and further polymerized them using n-hexanal (catalyzed by cation exchange resin) as a crosslinking agent. The effect of n-hexanal on the pour point and viscosity of crude oil was evaluated as a flow improver for crude oil. The addition of crude oil flow improver cation exchange resin catalyzed n-heptanal cross-linked polyamine amide has a certain pour point lowering effect in crude oil. PAA-87 has a good pour point lowering effect, and a 500 mg/L PAA-87 reduces the pour point of crude oil by 3.2 ℃. At the same time, it has a certain viscosity reducing effect in crude oil, among which PAA-97 has a better viscosity reducing effect and a viscosity reducing rate of 24.5%. Therefore, cation exchange resin catalyzed n-heptanal cross-linked polyamides can improve the flowability of crude oil.