Abstract: Based on Language Information Structure Theory and a contrast test of the acceptability of gapping data,this paper identifies that gapping exists in Mandarin Chinese.The linguistic context helps to improve and understand its acceptability.Mandarin Chinese gapping is a typical Topic-Comment Structure,and it transmits contrastive information by means of contrastive topic and contrastive focus.The roles of focus and the strength of contrastive information are the main factors affecting gapping's acceptability.Quantifiers,demonstratives and imperative mood can increase the acceptability by strengthening contrastive information.Adverbs,negators and effect-cause complex sentences can decrease the acceptability by influencing the roles of focus.