The invention discloses a method for treating garbage leachate. The method treats the garbage leachate by using the combined technique of pretreatment, biochemical treatment and advanced treatment, wherein the pretreatment adopts a method of coagulating sedimentation, reduces the concentration of organic matters, ammonia nitrogen and metallics, and reduces the inhibiting effect on the subsequent biochemical treatment; the biochemical treatment uses an anaerobic process, an A/O process and SBR to biochemically degrade wastewater, thereby simultaneously removing the organic matters and achieving the goal of denitrification; and finally, Fenton advanced oxidation and air flotation are used for carrying out the advanced treatment, and the strong oxidizing property of hydroxyl free radicals isutilized to oxidize the organic matters, which are difficult to be biochemically degraded, in waste water, thereby ensuring that the outlet water is discharged after reaching the standard. The invention has the advantages of simple operation of the technique, low operating cost, good treatment effect, no secondary pollution and the like, and the advanced treatment can ensure that the outlet wateris discharged after reaching the standard. The outlet water meets the standard for pollution control on the landfill site of municipal solid waste (GB 16889-2008).