The invention relates to a hydrophobic association polymer with double bonds on side chains. A method for preparing the hydrophobic association polymer includes regulating pH (potential of hydrogen) values of reactants of acrylamide, methacrylic acid, 2-acrylamide-2-methyl propane sulfonic acid, octadecyl acrylate and mixed solvents by the aid of NaOH solution at first and enabling the mass fraction of total monomers in reaction systems to range from 10% to 30%; adding sodium dodecyl sulfate into the reaction systems, then adding acrylamide derivative hydrophobic monomers with capasaicin functional structures into the reaction systems, introducing N2 to the reaction systems and then carrying out polymerization reaction to obtain the novel hydrophobic association polymer. The hydrophobic association polymer has the advantages that the hydrophobic association polymer is excellent in salt resistance and shear resistance, reaction can be carried out in the mixed solvents of ethyl alcohol and water, accordingly, the hydrophobic monomers are easy to dissolve, and the yield can be increased; each introduced hydrophobic monomer with the corresponding capasaicin functional structure is provided with carbon-carbon double-bond combination which does not participate in reaction, and accordingly the hydrophobic association polymer is excellent in viscosity increasing property, temperature resistance, salt resistance and anti-microbial performance and has an application prospect in oilfield development.