The current study aimed to explore the effect of first language (L1) orthography on second language (L2) Chinese morphological awareness. One hundred and twenty-nine students (61 L1 English readers and 68 L1 Thai readers) who studied Chinese as a second language participated in this study. They completed four tasks of morphological awareness (morpheme segmentation, morpheme discrimination, compound structure discrimination, compound structure analysis) and two control measures (reading vocabulary tasks). Drawing upon MANCOVA analysis, the study revealed that Thai readers outperformed English readers on compound awareness after the effect of L2 reading vocabulary was accounted for. The study suggests that L1 orthographic differences and similarities (e.g. interword boundary) may affect word identification, thus contributing to morphological processing of Chinese compound words. The study provided empirical evidence to support cross-language influence in morphological processing of a non-alphabetic language.