In this study, we evaluated the applicability of upflow percolation test of European Standard as one of waste landfill stabilization index. Landfilled waste samples were taken from an old uncontrolled waste landfill site before and after 1 month aerobic treatment. Diameter of 10 cm and height of 30 cm column was filled with landfilled waste sample, and the column was saturated with deionized water for three days to reach equilibrium. And then upflow leachant was flowed by peristaltic pump with a linear velocity of 15 cm/day. Given schedule of sampling times leachate was sampled several times, and pH, COD, NH4-N, and Cl− of leachate were analysed. At the same time AT4 test, which is test for aerobic biochemical stabilization index, was performed. Upflow percolation test and AT4 test for landfilled waste samples before and after aerobic treatment showed significant statistical difference of results. From the results, upflow percolation test might be used as an complementary waste landfill stabilization index with AT4 test, and database of landfilled waste sample with different landfill ages should be accumulated to setup the proper waste landfill stabilization index.