Complexation method for extracting pyrrolidone or its dissolved substance in organic dilute aqueous solution

The present invention discloses a method for recovering pyrrolidone and its solutrope from organic dilute solution by utilizing complexation extraction process. The organic dilute solution not only contains N-methyl pyrrolidone, but also contains C2, C3 alcohol, ethyl acetate and butyl acetate, also contains small quantity of oligopolymer, their total content is 5.0 wt%. Said invention uses Lewis organic acid or Lewis organic alkali as extracting agent, under the condition of that temperature is 15-50 deg.c, solvent-liquid ratio is 5:1-3 and pH value is 5.0-7.5 makes respective extraction, and under the condition of that the temperature is 70-210 deg.C, pH is 2.0-3.5 and pressure is 0.05-0.1 MPa makes back-extraction, the recovery rate of pyrrolidone and its solutrope in the organic dilute solution can be up to 60-90%.