The invention provides a two-stage treatment method for production wastewater, which includes the following steps: 1) reducing the pressure of the production wastewater, which is separated through a production separator, through an air floatation inlet ejector, and feeding the production wastewater into a rotational flow air floatation device for separation; 2) continuously discharging a continuous oil, bubble and scum layer, which is formed on the upper part in water in a pot body of the rotational flow air floatation device, into a sewage oil pot through a short pipe which is hung on the top and stretched into the pot, alleviating the separated water flow through a horizontal circular board in the middle-lower part, discharging the water through a water outlet, and feeding the water into a dual-medium filter through pressurization in a filter material feeding pump; and 3) when the treated water reaches a water injection standard, feeding the water into a degassing pot to mix the water with well water from a water source to perform reinjection, wherein back-wash water from the dual-medium filter is fed into the sewage oil pot. The two-stage treatment method has quick separation, good filter effects, strong sewage blocking capability, is stable in operation, is short in back-wash time and is complete in the back-wash, and is compact in equipment structure.