A method for controlling severe membrane fouling caused by membrane bioreactor mixed solution belongs to the water and wastewater treatment technical field. The method comprises two parts, namely the fast early-warning and regulation of the severe membrane fouling of the mixed solution. The early-warning is performed by adopting filter paper filtration index which can be fast monitored in the engineering site and the recommended early-warning value is 15-20ml. The regulation method comprises the following steps: firstly adopting the filter paper filtration index to perform the preliminary screening of regulators and obtain effective regulators, determining optimum dosage of each effective regulator, then testing the membrane filtration performance of the mixed solution samples with the added effective regulators, and comprehensively considering the improvement condition of the filter paper filterability and membrane filterability of the mixed solution after adding regulators and the costs of the regulators to select an optimum regulator used for regulating in site and inhibiting the generation of the severe membrane fouling. The method provided by the invention is fast, feasible, accurate and effective and can timely prevent and control the generation of the severe membrane fouling owning to the property of the mixed solution and ensure the engineering to run normally.