The invention discloses an eye drop which mainly contains amikacin or amikacin salt and chitosan or the derivative of chitosan. The eye drop comes into being through the dissolving of a medicine compound into the injection water which is then added with leakage pressure adjusting agent, pH value adjusting agent, acid-bases buffer, chemical inhibitor and bacteriostatic agent, then the addition of the full dose of injection water after the dissolving, then the filtering and sterilization of the solution, with the finished product obtained finally after the canning and sealing. The invention, on one hand, reduces the dosage of amikacin through the coordinate antibacterial action of chitosan, the derivative of chitosan and the amikacin, thus reducing the toxic and side effect and particularly reducing the toxicity to ears and kidneys. On the other hand, the invention prolongs the time for which the medicine stays in the eyes through taking advantage of the solution with a certain viscosity obtained after the dissolving of chitosan and the derivative of chitosan into the water, thus improving the use efficiency of the medicine, reducing the medicine using times and prolonging the intervals for medicine using. The invention has a good result in curing the eye infection caused by sensitive bacteria, such as conjunctivitis, keratitis, sclerotitis, etc.