Abstract This study investigates the effects of orthographic and phonological overlaps between the first language (L1) and the second language (L2) during word naming by adult Chinese-Japanese bilinguals, in the light of the Orthographic Depth Hypothesis which posits that the processing of printed words depends on the extent of grapheme-phoneme correspondence in the language. We compared their naming performance of L2 Japanese words written in moraic hiragana which is not used in their L1 Chinese, morphosyllabic kanji utilized in L1, and a mixed condition. Results indicated a longer latency for naming L2 Japanese words with kun-reading which has no phonological overlap with L1, particularly when written in kanji, which has orthographic overlap with L1. Consistent with the Orthographic Depth Hypothesis, participants performed better for words in hiragana as a shallow orthography than for words in kanji as a deep orthography. Furthermore, this study examined the priming effect of L2 Japanese translation equivalents on L1 Chinese targets. We found more accurate and faster naming of L1 words semantically exposed by L2, suggesting that L2 semantic representation facilitates L1 translation equivalence.