This study investigates the developmental trajectory of progressive construction among Chinese and Japanese EFL learners through a usage-based approach. A total of 600 written essays, produced by EFL learners from China and Japan with proficiency levels ranging from elementary to upper-intermediate, were analyzed. The findings reveal that advanced EFL learners, irrespective of their L1 backgrounds, exhibit higher productivity in using progressive constructions, aligning more closely with native English speakers. Moreover, the results support the aspect hypothesis, as activity verbs are predominantly marked with progressive across all learner groups. As for the development of progressive construction, less prototypical verb types in progressives increase proportionally with proficiency levels in the top 10 contingencies. However, discrepancies in proportions among Chinese and Japanese EFL learners underscore the need for a further examination of the intricate patterns of non-prototypical form-meaning associations across L1 backgrounds. The present study bears significance in shedding light on the acquisition of tense-aspect morphology influenced by L1 transfer and learner proficiency.