Recent research suggests that syntactic priming in language comprehension—the facilitated processing of repeated syntactic structures—arises from the expectation for syntactic repetition due to rational adaptation to the linguistic environment. To further evaluate the generalizability of this expectation adaptation account in cross-linguistic syntactic priming and explore the influence of second language (L2) proficiency, we conducted a self-paced reading study with Chinese L2 learners of English by utilizing the sentential complement-direct object (SC-DO) ambiguity. The results showed that participants exposed to clusters of SC structures subsequently processed repetitions of this structure more rapidly (i.e., larger priming effects) than those exposed to the same number of SC structures but spaced in time, despite the prime and target being in two different languages (Chinese and English). Furthermore, this difference in priming strength was more pronounced for participants with higher L2 (English) proficiency. These findings demonstrate that cross-linguistic syntactic priming is consistent with the expectation for syntactic repetition that rationally adapts to syntactic clustering properties in surrounding bilingual environments, and such adaptation is enhanced as L2 proficiency increases. Taken together, our study extends the expectation adaptation account to cross-linguistic syntactic priming and integrates the role of L2 proficiency, which can shed new light on the mechanisms underlying syntactic priming, bilingual shared syntactic representations and expectation-based sentence processing.