Abstract: A method for breaking the cell walls of microalgae includes cultivating microbes in a cultivating liquid, adding microalgae into the cultivating liquid to mix with the microbes, releasing a hydrolysis ferment from the microbes, hydrolyzing cell walls of the microalgae by the hydrolysis ferment of the microbes to decompose the cell walls of the microalgae into saccharide, and removing the microalgae from the cultivating liquid. Thus, the microbes release the hydrolysis ferment after the microalgae touch the microbes so as to hydrolyze and decompose the cell walls of the microalgae in a moderate manner without breaking the contents of the microalgae so that the contents of the microalgae can be released, absorbed and used completely.