This study investigated whether Chinese--Korean bilinguals can use structure-based information to interpret Korean sentences containing floating numeral quantifiers during online processing. A numeral quantifier in Korean can be stranded from its modified noun through scrambling as long as the quantifier forms a constituent with the noun. For Chinese--Korean bilinguals, acquiring this structural knowledge gives rise to a learnability problem because this ability cannot be derived from the L1, not easily induced from Korean input and is not obtained through classroom instruction. In acceptability judgment, highly proficient Chinese--Korean bilinguals demonstrated target-like knowledge of this structural constraint. Results from a self-paced reading task showed that the bilinguals showed sensitivity to the violation of the mismatch between an NQ and its modified NP, both in local and non-local dependency conditions. Our findings suggest that structure-based processing is possible for highly proficient bilinguals even when the target structure is not instantiated in bilinguals' L1.