This study explores the discrimination of Mandarin non-sibilant fricatives by bilingual speakers (N = 40) of Quanzhou Southern Min (L1) and Mandarin (L2) in different phonological contexts, including rounded vowels and the glide [w]. The results of the ABX discrimination task indicate significant contextual effects of the following sound, in line with predictions based on the Perceptual Assimilation model (PAM) [Best (1995). J. Phon. 20(3), 305–330]. Additionally, the observed result could not be fully explained by the acoustic distance between stimuli, and discrimination ability was better for speakers with more exposure to and use of Mandarin.