The invention provides a variable-frequency micro-wastewater treatment method, and belongs to the technical field of water purifiers, a wastewater outlet of a reverse osmosis filtering device is connected with one end of a wastewater drainage pipe, the other end of the wastewater drainage pipe is divided into a first branch pipe and a second branch pipe, the first branch pipe is connected with a raw water inlet of the reverse osmosis filtering device, and the second branch pipe is connected with a wastewater collecting device; a first valve is arranged on the first branch pipe, a second valveis arranged on the second branch pipe, and the first valve and the second valve are electrically connected with a controller; a first total dissolved solid detection device is arranged at a water inlet of a primary filtering device and is electrically connected with the controller. According to the variable-frequency micro-wastewater treatment method provided by the invention, the opening and closing interval time of the first valve and the second valve is flexibly adjusted according to the total amount of soluble solids in raw water, so that water resources are saved, and the service life ofa reverse osmosis membrane is prolonged. The invention also provides the variable-frequency micro-wastewater treatment method.