Language processing has been investigated in the psychological field by Western scholars in the past 50 years. And Chinese scholars began to do research in this field in the 1980s. In recent times, sentence processing has been a hotspot in psycholinguistics. To many linguists, sentences that violate syntactic constraints are clearly distinct from sentences that violate semantic constraints. Whether this distinction characterizes accurately the processes underlying sentence comprehension has been a matter of debate. Different models of sentence processing have been proposed, among which three kinds of theories are the most influential, i.e. modularity theories, interactive theories and concurrent theories. Moreover, one of the two fundamental tenets of modern-day psycholinguistics is the belief that syntactic processing always precedes semantic processing.In this thesis, two experiments are done to investigate detection of syntactic violation and semantic violation in English and Chinese relative clauses by Chinese English learners. The subjects are fifteen students who are English postgraduates in Zhejiang University. They were asked to read 260 Chinese sentences in the first experiment and 260 English sentences in the second experiment. The results reveal that different from English sentence processing mechanism, Chinese processing mechanism is a semantics-first one. The study also indicates that Chinese processing mechanism may have an effect on English sentence processing, and other factors such as teachers’ instruction and learners’ second language proficiency may play a role as well. Research implications and suggestions for further study are also presented.