The invention relates to a preparation method of a slow-rebound sponge, particularly a preparation method of a bamboo charcoal slow-rebound sponge. The method comprises the steps of respective weighing, respective stirring, respective feeding, foaming and cooling. The method specifically comprises the following steps: evenly mixing a first polybasic alcohol and a second polybasic alcohol in a stirrer to obtain a first mixed solution, and evenly mixing bamboo charcoal powder, MDI (methylenediphenyl diisocyanate), a foaming agent, a catalyst, a surfactant, a flame retardant and 0.2-0.8 part by weight of silicon rubber toughener in a second stirrer to obtain a second mixed solution; sending the first mixed solution into a first feed pipe, sending the second mixed solution into a second feed pipe, foaming in a 40-50 DEG C foaming mold for 1-8 minutes, and keeping the temperature of 25-40 DEG C for 1-5 hours; and cooling, and dicing. The bamboo charcoal slow-rebound sponge has the advantages of favorable air and moisture permeability, low rebound speed and proper softness and hardness, and is slightly influenced by the temperature.