The invention discloses a high-efficiency mould-proof preservative special for preserving garlic stems, which consists of the following components in percentage by weight: 1 to 5 percent of chitosan, 0.05 to 0.1 percent of nipagin ester, 0.001 to 0.01 percent of natamycin, 0.05 to 0.1 percent of thiabendazole and the balance of water. The garlic stem preservative has low cost and is convenient to apply and high-efficiency and safe; by combining measures and technology such as low temperature, spontaneous modified atmosphere packaging and the like, the garlic stems treated by the preservative are bright green, have tender tissues and are still fresh after being stored for 6 to 8 months, and mould does not grow in garlic involucre and strips; the commodity rate reaches 95 percent; and the preservation effect is good.