Recent research has uncovered relation-based conceptual combination in L1 English speakers’ processing of noun–noun compounds. However, it remains unclear whether Chinese EFL learners undergo a similar relation-based conceptual combination when processing English noun–noun compounds, particularly given the similarities in compounding between English and Chinese. To address this inquiry, a cohort of 120 Chinese EFL learners with advanced and intermediate English proficiency were requested to interpret English noun–noun compounds online in contexts with modifier-based relational information only, or both modifier- and head noun-based relational information. Results showed that Chinese EFL learners’ processing relied heavily on available relational information. Moreover, both modifier- and head noun-based relational information contributed to this process but played distinct roles at different phases, modulated by task demands. While English proficiency affected processing speed, both proficiency groups exhibited a similar pattern across experiments. These findings shed light on the nuances of L2 learners’ conceptual combination of English noun–noun compounds.