The invention discloses a highly pure polymer-grade n-hexane production method to solve the problems of complex technologies, dissolving, degradation and the like in the prior art. The method comprises the following steps: carrying out heat exchange on crude n-hexane with n-hexane content of 60-90wt% as a raw material, allowing the heat-exchanged crude n-hexane to enter an isohexane removal tower, allowing light component removed crude n-hexane flow from the bottom of the isohexane removal tower to enter an extracting rectifying tower, allowing the light component removed crude n-hexane flow to contact with N-methyl pyrrolidone, separating and purifying n-hexane in the light component removed crude n-hexane, recycling the solvent N-methyl pyrrolidone from the extracting rectifying tower, and purifying purified n-hexane to obtain polymer-grade n-hexane.