A two-stage urea-selective catalytic reduction(SCR) system and a related control strategy were developed as an alternative solution to fulfilling the China Ⅵ emissions regulation. Experiments were proceeded to validate the developed system performance in converting NOx and to investigate the influence of the new system on diesel particulate filter(DPF) passive regeneration. The results show that during the world harmonized transient cycle(WHTC) the efficiency of converting NOx by the new system reaches up to 89.2% at cold start and up to 99.3% at hot start

5.4% and 3.0% respectively higher than those of the conventional system. The total WHTC emissions are lower than those of the China Ⅵ emissions regulation

which indicates the new system has the potential to satisfy the further emissions legislation. When a closed-loop control is adopted for the urea injection

the two-stage urea-SCR system has only 0.2 g/L higher soot loading than the conversional system at DPF balance point under WHTC cycle

exerting very limit influence on the DPF passive regeneration performance.