This qualitative dissertation sought to understand how twenty-five junior and senior STEM major students perceive and experience critical thinking. It utilized a transcendental phenomenology approach and analyses to answer the following research questions: How do Chinese international and domestic junior and senior STEM students perceive and describe critical thinking? Do the two groups both believe critical thinking has an important impact on their education and life in general? What suggestions do the two groups have for their instructors to facilitate their critical thinking comprehension and application? The research employed a transcendental phenomenology approach that enabled me, as the researcher, to be more reflective of my own prejudgment and pre-knowing towards the study and participants, and to explore how students themselves experience the concept of critical thinking to gain a clear understanding of their curriculum and learning. The results showed that they understood and experienced critical thinking as a way of thinking, problem solving, a process, and also a confusing concept. All participants thought critical thinking was important for their education and career, but less important for their everyday lives. Participants valued their authentic research and learning experiences, interactions with their instructors and meaningful small group activities from their curriculum.