The invention discloses a high-efficiency microbubble air flotation oil and suspended matter removal system and process for salt-containing wastewater of an oil and gas field. The system comprises a regulating water tank, a lifting pump, a microbubble air floatation separation tank and a sludge pump, which are sequentially connected. An efficient cyclone mixer is arranged between the water outletend of the lift pump and the water inlet end of the microbubble air flotation separation tank. The efficient cyclone mixer is respectively connected with the air compressor and the dosing and meteringdevice. A slag scraper is arranged at the top of the microbubble air flotation separation tank, a sludge hopper is arranged below the slag scraper, and the sludge hopper and the microbubble air flotation separation tank are connected with a sludge pump through pipelines. A pH on-line instrument and a liquid level meter are arranged in the water tank. Compared with the prior art, the system and the process have the positive effects that the investment is saved, the occupied area is small, the effluent quality is stable, the management and the operation are convenient, the automatic control canbe completely realized, and the problem of removing oil drops and suspended solids in various sizes is thoroughly solved.