NOVELTY - Preparing acetic acid-lysine pharmaceutical active ingredient involves preparing aqueous solution of lysine hydrochloride and carrying out dechlorination by electrodialysis system to obtain aqueous solution of lysine. The lysine is added to glacial acetic acid solution and reaction is carried out to obtain aqueous solution of acetic acid-lysine. The aqueous solution of acetic acid-lysine is subjected to nano-filtration through pharmaceutically activated carbon adsorption filter and then subjected to ultra-filtration to obtain super acid lysine pharmaceutical active ingredient (API) filtrate.    USE - Method for preparing acetic acid-lysine APIs used for preparing lysine acetate API solution (claimed).    ADVANTAGE - The method enables to prepare acetic acid-lysine APIs in eco-friendly manner that has high light penetration rate and high quality.    DETAILED DESCRIPTION - Preparing acetic acid-lysine pharmaceutical active ingredient involves preparing aqueous solution of lysine hydrochloride and carrying out dechlorination by electrodialysis system to obtain aqueous solution of lysine. The lysine is added to glacial acetic acid solution and the reaction is carried out to obtain aqueous solution of acetic acid-lysine. The aqueous solution of acetic acid-lysine is subjected to nano-filtration through pharmaceutically activated carbon adsorption filter and then subjected to ultra-filtration to obtain super acid lysine pharmaceutical active ingredient (API) filtrate. The obtained filtrate is segmented and concentrated under vacuum. The filtrate is crystallized, separated and vacuum-dried under reduced pressure to obtain acetic acid-lysine APIs. An INDEPENDENT CLAIM is included for a method for preparing lysine acetate API solution, which involves:    (A) subjecting acetic acid-lysine API solution to first stage evaporation at 50-70 degrees C and concentrating solution to saturation critical point;    (B) subjecting acetic acid-lysine API solution to second stage evaporation at 70-80 degrees C and concentrating to 60%; and    (C) cooling concentrated solution overnight to obtain wet crystals of lysine acetate solution.