Corpus-based behavioral profile analyses can fully reveal the subtle differences of a group of synonyms. Taking possible, probable and likely as examples, this study analyzes their differences in usage patterns based on the data from the British National Corpus (BNC) by adopting the behavioral profile analysis. The results show that: (1) Probable and likely are more similar in usage patterns, and probable is different from them; (2) Possible tends to be used as a complement, often used with personal pronouns and abstract nominal objects, probable tends to be used as an attribute, while likely tends to be used as a predicative, and tends to be used with personal pronouns and inanimate nominal subjects; (3) When used as an attribute, probable tends to modify nouns indicating results, people, money and value; probable tends to modify nouns indicating money and benefits, methods, politic initiatives; while likely is often used as an attribute to modify nouns of people, results, money, influence and region, and the degree of possibility expressed by likely is in the middle of the three.