A method for removal of metal ions from rice hull. 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 hull, placing it in the water storage reactor, and pressing down on the bagged rice hull 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 the amount of carbon dioxide dissolved in per 100 g of water is about 1 g, whereby generating a carbonic acid solution; 4) allowing the carbonic acid solution to react with metal ions in the rice hull to yield a precipitate; and 5) washing the rice hull collected in step 4), washing again with desalinated water, and then squeezing the rice hull.