The invention relates to methods of plant vegetative propagation, and provides a liquid cuttage method for a pineapple single leaf. The liquid cuttage method comprises the following steps: (1) growing and culturing of buds: selecting a mature pineapple, taking off the healthy crown bud of the pineapple, cutting off and taking a single leaf with an axillary bud along the growth direction from the crown bud by an operating knife, fully drying, placing in a seedling-growing disk with a bud growing culturing liquid of a 1/2MS liquid nutrient solution containing IBA and NAA, and changing the culturing liquid once a week; (2) rooting culture: when a seedling grows up to 5-10 leaves, transferring the seedling to a rooting culture liquid of a 1/2MS liquid nutrient solution containing IBA and NAA; and (3) transplanting and hardening the seedling, when the root grows up to 2-3 cm, transplanting to a solid culture base for hardening the seedling. The characteristics of the liquid cuttage method comprise that: (1) by using the single leaf for cuttage, a mass of cuttage materials are saved; (2) the liquid cuttage method helps to reduce the contact with mediums such as soil and the like, and reduce influence of microbes on breeding materials, and is relative simple and convenient; and (3) the liquid cuttage method is simple in operation flow, time-saving and labor-saving.