The invention discloses a well sealing process method of a chemical flooding injection well. The method comprises the steps that a predetermined concentration of oxidant is injected into a wellbore, acasing scraper is cooperated to treat wall-hanging polymer of the wellbore, a pipe column of the wellbore is raised to a predetermined distance above an upper boundary of an oil layer through a clearwater circulation, and perforating positions are unblocked by using a blockage-removing agent; after blockage-removing is completed, an ash squeezed pipe column is lowered into the wellbore, clear water is pressurized to squeeze the oil layer as a test, and the inhalation amount of stratum is tested; when test squeezing meets requirements, a temporary blockage-removing agent is injected to conduct temporary blockage treatment; cement slurry is injected into the wellbore, the injected cement slurry is injected in sequence, and proportion of the cement slurry increases in sequence; the cement slurry, main gluing cement slurry and wellbore sealing congealing waiting cement slurry are placed at front. The well sealing process method of the chemical flooding injection well can successfully complete sealing of the injection well at a time, and meet various technical indexes and test indexes of well sealing.