As one type of the most extensively used sentences, English questions are must-learn grammatical structures for learners of English as a foreign language (EFL). However, it is commonly seen that English learners across proficiency levels produce ungrammatical English questions. To determine the source of learners' erroneous production, we conducted a written test to collect hands-on data of four types of English questions produced by 81 Chinese EFL preliminary learners. Learners' achievement scores showed that learners from both higher and lower proficiency groups had similar difficulty producing questions. The statistics also showed morphosyntactic inconsistencies in learners' production were congregating on auxiliaries' choice and tense variation. Cross-linguistic transfer from first language (L1) in English question acquisition for Chinese EFL learners was measured against the three dimensions of Jarvis' (2000) methodological model. Influence from learners' L1 was found to be related to preliminary learners' morphosyntactic inconsistencies. The findings suggest that practitioners in an EFL context should raise learners' grammatical consciousness, and design production-oriented tasks, to improve learners' morphosyntactic accuracy in English question formation.