Wastewater filtering treatment system and method

The invention relates to a wastewater filtration treatment system and method, and the method at least comprises the following steps: first-stage separation: separating at least part of hardness and sulfate radicals from first-stage separation inlet water through a monovalent ion selective nanofiltration membrane in a phase-change-free manner, so as to at least obtain first-stage separation produced water; second-stage separation: introducing the first-stage separation produced water in the form of second-stage separation inlet water, and separating a solute and a solvent in the second-stage separation inlet water by externally applying a pressure higher than the osmotic pressure of the solution so as to at least obtain second-stage separation concentrated water; third-stage separation: introducing the second-stage separation concentrated water in the form of third-stage separation inlet water, and driving charged ions in the solution to directionally migrate through an externally applied electric field so as