With the development of technology, Duolingo has become an important trend in global education. The software Duolingo is a good example of mobile-assisted language learning. Therefore, this study takes Duolingo, a language learning application, as the research object. Through the SWOT analysis model, the four directions of internal strengths and weaknesses, external opportunities and threats are explored in depth. The study analyses Duolingo through secondary data, including academic literature, company reports and industry information. The study finds that Duolingo's strengths are the availability of multiple languages for learning, a large user base and an impressive brand image. However, it also suffers from a lack of life-like dialogue teaching, poor results for speaking enhancement skills and AI difficulties for speech recognition. In the external environment, the development of online testing and personalised learning brings new opportunities, but also faces the challenge of being replaced by translation tools and customers will lose interest in Duolingo. The study concludes that Duolingo has a solid competitive position in the overall field of mobile-assisted language learning, but will need to continue to innovate and optimise its product strategy in order to achieve long-term sustainability.