The invention discloses a method for cultivating iron oxidized leaching microorganism. The method comprises the following steps: the leaching microorganism is cultured in a medium to the end of a logarithmic phase of the microorganism, the iron powder is added, the pH is adjusted, and the steps of stirring and aeration culture are stirred; adding calcium carbonate powder to adjust the pH to 2.0-2.5, stirring the material, and performing standing to obtain a supernatant and the sludge at a lower part, filtering the sludge to obtain filter residue and a filtrate, merging the supernatant and thefiltrate and performing continuous aeration culture; repeating the above steps, returning the filter residue to the next round of precipitation process until the concentration of microorganisms in thesupernatant reaches the requirement, and performing last culturing to obtain the supernatant and the filtrate obtained by filtering the sludge at the lower part as a bioleaching agent. The method employs a precipitation method to reduce the adsorption, agglomeration and retention of microorganisms on the solid surface, reduces the loss of microorganisms, and has good precipitation and filtrationproperty, and the concentration of microorganisms in the bioleaching agent reaches 109 cells/mL or more.