以中型柴油机为平台，以现行国六排放法规为依据，研究柴油氧化催化剂（DOC）起燃特性的影响因素。针对DOC催化剂不同的涂覆方式及贵金属不同比例，设计了3种不同涂覆方式的DOC催化剂，记为方案A、方案B、方案C，3种方案的贵金属总含量相同，方案A和方案B中前后区的贵金属Pt和Pd比例不同，方案C中提高了Pt的比例。进行了两个阶段的老化试验，研究了在不同工况条件下3种涂覆方式DOC的起燃特性。结果表明：A、B、C 3种涂覆方式的DOC催化剂都能满足起燃性能，B、C两个涂覆方案的HC转化效率较高，催化剂起燃性能较好，对于保证起燃以及对HC泄漏的控制有一定的优势。

The influencing factors  for the light-off characteristics of diesel oxidation catalyst (DOC) were studied on a medium-duty diesel engine according to the current China Ⅵ emission regulation. According to the different coating methods and noble metal proportion of DOC catalyst, three different schemes were designed which were labeled as Plan A Plan B and Plan C respectively. The total noble metal content of three schemes was the same. The proportions of Pt and Pd were different in front and back zone for Plan A and Plan B, and the proportion of Pt increased in Plan C. Besides, the aging tests were carried out in two stages respectively, and the light-off characteristics were studied under different working conditions. The results show that the DOC catalysts of three coating methods from Plan A, Plan B and Plan C can meet the lightoff performance requirements. Plan B and Plan C have higher HC conversion efficiency and better lightoff performance, which have certain advantages for guaranteeing lightoff and controlling HC leakage.