The present invention relates to a preparation method of a high-stable non-ionic N-vinyl butyrolactam iodine, wherein non-ionic N-vinyl butyrolactam, iodine and at least one grinding aid are stirred at 150-800 r/min at a temperature of 50° C.-90° C. for 1 to 12 hours to prepare the high-stable non-ionic N-vinyl butyrolactam iodine, wherein the K value of the non-ionic N-vinyl butyrolactam is 32±1, the PD value of the main peak of the non-ionic N-vinyl butyrolactam is ≦1.6, the moisture content of the non-ionic N-vinyl butyrolactam is ≦2.5%, preferably, the grinding aid is selected one or several from sodium chloride, sodium citrate, sodium carbonate and sodium phosphate, the amount of the grinding aid added is 0.02 to 2% of the total amount of the non-ionic N-vinyl butyrolactam and the iodine, the non-ionic N-vinyl butyrolactam is PVP-K32, the high-stable non-ionic N-vinyl butyrolactam iodine prepared by the above mentioned method is also provided, the stability of the high-stable non-ionic N-vinyl butyrolactam iodine of the present invention is high, thereby facilitating long-term storage and use, thus the high-stable non-ionic N-vinyl butyrolactam iodine is suitable for large-scale popularization.