While phonetic training in laboratory settings has been shown to be helpful for second language (L2) sounds learning in prior studies , it is still open to debate whether a perception- or a production-based approach can better help adults learn L2 sounds in classroom settings. This study aimed to fill this knowledge gap. The participants were three groups of adult Chinese college students who had difficulties in perceiving and producing English/?/-/s/and/ð/-/z/. Group 1 and Group 2 were exposed to a perception-based and a production-based training approach respectively. Group 3 was the control group (no training). The training materials were "minimal pairs" embedding the target contrasts in various phonetic environments. Each session included explicit articulatory instructions and perception- or production-based practice activities. Individual participants' perception and production of the target contrasts were tested before (pretest), after (posttest), and one month after the training programme (delayed posttest). According to the results, (1) in comparison with the pretest, both the perception- and production-based groups showed significant perception and production improvement in the posttest, which remained in the delayed posttest; the control group had no significant perception or production changes across the three tests; (2) the production-based group had significantly better perception and production performance than the perception-based group both in the posttest and the delayed posttest. The overall results suggest that a production-based approach may be optimal for L2 sounds learning.