Simultaneous interpreting with text or slides is a complex form of bilingual language processing due to its dual input. The present study seeks to explore the processing and rendering of asymmetrical structures in SI with slides. To achieve this, we first investigate asymmetrical structures in Chinese-English SI with slides in both directions. Then, we examine whether the processing of asymmetrical structures generates a spillover effect on the continuation segment, and how the spillover effect varies with the interpreting direction. Twenty interpreting students were invited to perform tasks of SI with slides in an eye-tracking experiment. The results show that (1) the processing of asymmetrical structures was more challenging in L2–L1 SI with slides than in L1–L2 SI with slides; (2) asymmetrical structures had a spillover effect on the processing of the subsequent segment; (3) the spillover effect was greater in L2–L1 than in L1–L2 SI with slides. The findings provide new insights into the processing of syntactic asymmetry in an interpreting mode with dual input. Our results also suggest that asymmetrical structures might be potential causes of the spillover effect.