Ultrafiltration　(UF)　is　a　high-potential　technology　for　purifying　natural　surface　water;　however,　the　problem　of　membrane　fouling　has　limited　its　widespread　application.　Herein,　ultraviolet　(UV)-activated　ferrate　(Fe(VI))　was　used　to　purify　natural　surface　water　and　improve　the　performance　of　the　UF　membrane.　The　combination　of　UV　and　Fe(VI)　could　generate　active　species　(Fe(V),　Fe(IV),　(OH)-O-center　dot　and　O-2(center　dot)-)　to　degrade　pollutants,　while　the　in　situ　produced　Fe(III)　had　the　effect　of　coagulation.　With　the　above　action,　pollutants　were　removed,　and　the　pollution　load　of　natural　surface　water　was　reduced.　After　treatment　with　the　UV/Fe(VI)　system,　dissolved　organic　carbon　was　reduced　by　49.38%,　while　UV254　was　reduced　by　45.00%.　The　removal　rate　was　further　increased　to　54.88%　and　51.67%　after　UF　treatment.　In　addition,　the　fluorescent　organics　were　reduced　by　44.22%,　and　the　molecular　weight　of　the　organics　became　smaller.　In　the　stage　of　UF,　the　terminal　J/J(0)　was　increased　from　0.61　to　0.92,　and　the　membrane　fouling　resistance　was　decreased　by　85.94%.　The　analysis　of　the　membrane　fouling　mechanism　indicates　that　the　role　of　cake　filtration　was　weakened　among　all　the　mechanisms.　Fourier　transform　infrared　spectroscopy　showed　that　less　pollutants　were　accumulated　on　the　membrane　surface,　and　scanning　electron　microscopy　revealed　that　the　membrane　pore　blockage　was　relieved.　In　summary,　the　UV/Fe(VI)　co-treatment　process　proposed　in　this　study　can　significantly　improve　the　purification　efficiency　of　the　UF　systems　in　natural　surface　water　treatment.