The invention discloses a microwave annealing preparation method of an NCC/PVA/PVP blended carbon sponge capable of efficiently removing heavy metal ions and organic dye in water. The method includes the steps that firstly, microcrystalline cellulose is prepared into nano-crystalline cellulose suspension according to a sulfuric acid method; secondly, polyvinyl alcohol is added into the suspension obtained in the first step; thirdly, polyvinylpyrrolidone is added into the suspension obtained in the first step; fourthly, the suspension obtained in the second step and the suspension obtained in the third step are proportionally mixed and then subjected to microwave annealing treatment, and the nano-crystalline cellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge can be obtained. The blended carbon sponge prepared according to the preparation method has a stable shape, the product purity is high, and the removal rate on heavy metal ions and organic solvents is high.