The invention relates to the field of organic synthesis and medicinal chemistry, in particular to a derivative of Cleistanine, a preparation method and application of Cleistanine in preparing anti-bacterial medicines. According to the invention, a novel Cleistanine derivative is synthesized, and the invention discloses the preparation method thereof; the pharmacological experiments show that the derivative of Cleistanine has antibacterial effect and value for developing anti-bacterial medicines.