Inflectional morphology is the modification of a word to fit its grammatical role. By adding suffix, they mark properties such as tense, number, gender, case, and so forth. Compared to native English speakers, it's difficult for second language learners to process inflected words even when they study abroad for many years. Previous studies suggested the processing of inflections involved two different memory systems: declarative memory system for storage of word knowledge and procedural memory system for processing of grammar, syntax and rules. For late second language learners, they rely more on declarative memory system to process inflections. However, whether the processing will turn into procedural processing, and what kind of rules or inflections can be processed by procedural memory system, these are all not clear. According to Ullman (2004), ERP patterns can reflect the mechanism of inflection processing through different patterns of component, such as latency and scalp distribution. Therefore, the present study adopted ERP measures to examine Chinese learners’ processing of English verbal inflections (the inflection of verb progressive tenses, -ing; the inflection of regular verb perfect tenses, -ed; and the inflection of irregular verb perfect tenses). Moving window paradigm was used in this research. Sixteen Chinese students who learn English as a second language participated in the experiment; they completed a grammatical judgment task, and ERPs were recorded by NeuroScan system at the same time. The materials contain 408 sentences, with 48 sentences per condition (grammatical/ungrammatical sentences with -ing; grammatical/ungrammatical sentences with -ed; grammatical/ungrammatical sentences with irregular verb inflections in perfect tense). Behavioral results suggested that, for late English learners, the processing of –ing are better than the other two inflections. ERP results showed that, the violation of -ing caused the component of P600, the violation of -ed caused the component of N400, while the violation of irregular verb perfect tenses didn’t produce any significant ERP components. Based on these findings, we concluded that the inflection of verb progressive tenses, the inflection of regular verb perfect tenses and the inflection of irregular verb perfect tenses which have no obvious affix do not share the same processing mechanism, the difference across English verbal inflections may be related to the complexity of inflectional rules.