The present study presents two experiments that investigated the influence of sentence presentation speed on English syntactic processing of late Chinese-English learners in order to test L2 processing speed on the influence L2 syntactic processing. In Experiment 1, sentences were displayed word by word with two different speeds in visual presentation. One condition was fast speed of presentation, that is to say, each word was presented for 250ms; the other was slow speed of presentation, that presentation time for each word was 500ms. Sixty university students participated to read these sentences, thirty in each group. In Experiment 2, participants were instructed to listen to sentences with normal and rapid speed in auditory way. The rapid speed of reading is 1.5 times as normal. Fifty-two university students participated, twenty-six in each group. There were 8 different forms of syntactic structure, including article, regular and irregular past tense, regular and irregular plurals, third person singular, present progressive and word order. All the sentences of 8 different forms of syntactic structure were divided into two forms: one is right and the other is wrong forms. Grammatical judgment task was used. The results of two experiments indicated that sentence presentation speed played a critical role in L2 syntactic processing. Specifically speaking, eight different forms of syntactic structure were all influenced by speed of sentence presentation, the faster sentences displayed, the worse syntactic processing was performed. The difference of processing difficulty exists among different syntactic structures: it’s easier for present progressive to process, whereas much harder for article and irregular plurals. These results provided the evidence that processing speed is an important factor to influence L2 syntactic processing.