There are problems of high injection pressure and low recovery in the process of tight oil reservoir displacement. Olefin ester oil displacement agents was proposed to apply to the displacement development of tight oil reservoirs. Taking 9-decenoic acid methyl ester as an example，through tight core flooding experiments，the advantages of the injection pressure and oil displacement effect of olefin ester flooding agents over conventional oil flooding agents in the process of tight core flooding were studied. 9-decenoic acid methyl ester is insoluble in water and can be miscible with organic solvents such as ethanol，ether，acetic acid， etc.，and can rapidly transfer mass to the depth of the core during the displacement process. The research results showed that for the tight core with the permeability level of 0.1 × 10^-3 μm² ，the displacement pressure of 9-decenoic acid methyl ester was greatly reduced compared to conventional oil displacement agents，being of less than 1/30 of the water flooding pressure，which was suitable for the flooding of tight oil reservoirs. The flooding experiment showed that，by injecting 2 PV 9-decenoic acid methyl ester first and then water flooding，the oil recovery rate of 9-decenoic acid methyl ester flooding reached more than 80% ，and the comprehensive oil recovery rate reached more than 90%. After water flooding，0.3 PV and 1.5 PV 9-decenoic acid methyl ester slugs were injected to increase oil recovery to 20.61% and 57.52%，respectively. Ester oil-displacing agents had good injection adaptability in the development and application of tight oil reservoirs，and at the same time could greatly improve the degree of recovery，and have broad application prospects.