The invention discloses walnut shell extracting solution and application of the solution in cigarette, and relates to extraction and application of flavor for the cigarette. The walnut shell extractinbg solution is a light brown liquid with pH value of between 6.5 and 7. The extracting solution of the walnut shell is extracted by the following steps: (1) grinding a walnut shell to particles of between 30 and 50 meshes; (2) preparing zymotic fluid with microzyme concentration of between 2 and 5 percent at a temperature of between 33 and 37 DEG C; (3) sealing the particles of the walnut shell and the zymotic fluid, according to proportion that the particles of the walnut shell to the zymotic fluid is 3 to 5; (4) shaking the mixture every 12 hours; (5) fermenting the mixture for 8 to 12 days; and (6) filtering the mixture after fermenting the mixture, and heating and boiling the mixture for 2 hours. The extracting solution of the walnut shell is used as feed liquid with dosage of 0.2 to 0.5 percent of total volume of tobacco leaves. The walnut shell extracting solution and extraction and application of the solution in cigarette have the advantages of simple method, easy implementation, scrap utilization, positive effect on tobacco, low cost and convenient use, and is a positive measure of changing waste into valuable.