Provided is a method for producing a modified graphene, comprising the steps of intercalating or inserting a mixture of intercalating agents in a spacing between interlayers of carbon substrates or between carbon substrates, whereby the binding force between the interlayers of the carbon substrates or between the carbon substrates is weaken; and then exfoliating the pretreated carbon substrates to form the modified graphene. Upon environmental friendly purpose, the method according to the present invention is useful for reducing the total amount of strong acid. Therefore, the amount of the generated oxygen-containing functional groups attached on the modified graphene is modulated to avoid defects and maintain a yield over 80%.