One of the biggest challenges encountered by second language learners is to accurately differentiate between the two vowels in English: /i:/ and //, which play an important role in everyday communication and are crucial for clear transmission of information and effective communication due to their high functional load (FL). Therefore, the paper aims to gain a more profound understanding of the difficulties learners encounter in distinguishing these vowels, with the hope of providing them with more effective learning strategies and methods. In this paper, seven English majors and seven non-English majors were selected as the study participants using an empirical research method, and audio data on the participants' pronunciation of words containing /i:/ and // were collected using a recording device and analyzed using Praat. The results indicates that both groups frequently lacked an understanding of the distinctive pronunciation characteristics of these vowels, which resulted in instances of pronunciation confusion or inaccuracy. Moreover, it proposes suggestions for enhancing teaching strategies: the integration of audio and visual teaching resources and the implementation of targeted pronunciation exercises can facilitate the acquisition of English pronunciation, thereby enhancing the accuracy and fluency of their spoken English and their performance in English communication.