The invention discloses a micro flocculation, membrane filtration and air flotation integrated reaction device and a method for treating low-turbidity micro-polluted water by using the same, relating to a water treatment device and a method for treating low-turbidity micro-polluted water by using the same. Through the invention, the problem that the concentrated solution in the reaction pools needs to be discharged periodically in the traditional micro flocculation and immersed ultra/micro filtration membrane processes is solved. The device comprises a micro flocculation, membrane filtration and air flotation integrated reaction tank which consists of a mechanical micro flocculation area, a transition area and a membrane filtration-air flotation area, wherein an ultra/micro filtration membrane is arranged in the membrane filtration-air flotation area; and a releaser is arranged at the bottom of the membrane filtration-air flotation area and communicated with a water storage tank through a dissolved-air pump. The method comprises the steps: the low-turbidity micro-polluted water is flocculated and enters the membrane filtration-air flotation area; and then an ultra-micro filtrationmembrane assembly works together with the dissolved-air pump to complete the water treatment; or the ultra-micro filtration membrane assembly works firstly and then the dissolved-air pump works to complete the water treatment. By means of the invention, the in-situ purification of the concentrated solution is realized and the floor area is saved.