This is a prospective, randomized, multi-center intervention study. 400 maintenance hemodialysis patients with twice dialysis sessions per week will be enrolled into the study. All the patients have their baseline Kt/V between 1.2 and 1.7 (1.2 ≤ Kt/V ＜ 1.7). After treatment intervention, the patients will be randomized to two groups according to their different Kt/V (1.2 ≤ Kt/V ＜ 1.7 vs. Kt/V ≥ 1.7), then the patients will be regularly followed up at baseline, 12 weeks, 24 weeks, 48 weeks, 72 weeks and 96 weeks. Clinical outcomes such as mortality, complications and life quality between the two groups will be investigated.