A method for removal of metal ions from rice hulls. The method includes: 1) providing a water storage reactor, and disposing a gas dispersion device at the bottom of the water storage reactor; 2) bagging rice hulls, placing it in the water storage reactor, and pressing down on the bagged rice hulls to be lower than a water surface in the water storage reactor; 3) spraying industrial flue gas into the water storage reactor; controlling the amount of the industrial flue gas such that about 1 g of carbon dioxide is dissolved per 100 g of water, thus generating a carbonic acid solution; 4) allowing the carbonic acid solution to react with metal ions in the rice hulls to yield a precipitate; and 5) washing the rice hulls collected in step 4), washing again with desalinated water, and then squeezing the rice hulls.