ESP(English for Special Purposes) teaching involves English language teaching in different professional fields. The teachers are expected not only to convey the language knowledge, but also to explain the professional terms and knowledge in English. This paper takes Business English course as an example to explore the feasible teaching models by use of mobile devices like smart phones. The writer first reviewed the researches on ESP teaching and mobile learning. Then the status quo and problems in the traditional business English teaching were discussed. The writer further attempted the design of mobile learning model in business English teaching from the perspectives of vocabulary, listening, speaking and reading and writing. And the features of mobile learning in ESP were summarized based on the discussion above. The introduction of mobile learning model into ESP teaching is a trend in modern world which will increase students' interest in English learning and the teaching effect will be enhanced as well.