The invention provides a method for treating caprolactam production wastewater. The method comprises the following steps of (1) salting-out: adding inorganic salt into a reactor, while continuously leading the caprolactam production wastewater and/or reflux liquid, continuously evaporating moisture, and precipitating organic matters in the wastewater in a floccule form under the salting-out function; (2) flocculating: continuously leading the wastewater containing the floccule into an overflow tank, adding a flocculant into the overflow tank, flocculating and settling suspensions containing the floccule in the wastewater, and enabling the supernatant of the overflow tank to flow back to the reactor; (3) thinning the wastewater subjected to salting-out and flocculating, sending into a membrane biological reactor, and further performing biochemical treatment, wherein the membrane biological reactor comprises an A/O biochemical system, a dynamic membrane filter, a dynamic membrane preparation system and a hydraulic backflushing device. The method has the advantages that the energy consumption is low, the operation cost is low, and a large amount of caprolactam wastewater can be effectively and quickly treated.