Xuan Son landfill, Hanoi has been operating since 2000. However, the quality of wastewater after treatment at Xuan Son landfill does not meet discharge requirements regarding some principal paramf!ters (COD, BOD5, N-NH4+, total N, and total coliforms). The results of survey and evaluation processes showed that the actual wastewater flow significantly exceeded the design capacity. Applied technology at Xuan Son landfill are inadequate. It is necessary to add clusters for nitrogen and first physical chemical treatment on the basis of upgrading facilities in the current wastewater treatment plant. Periodical monitoring is required to ensure that the quality of wastewater after treatment satisfies the regulations in B1 column of QCVN 25:2009/MONRE.