AbstractGender gaps in STEM fields have been studied for a long time, and the primary focus has been on the relationship among social support (parents and teachers), STEM beliefs (STEM interest belief, self‐efficacy belief, and value belief), and STEM career expectations. Framed in Expectancy‐Value Models, this article aimed to explore how social support affects students' STEM career expectations directly and indirectly through STEM beliefs. Further, a gender study was conducted to examine the differences in structural relations between male and female student groups using multiple‐group structural equation modeling. A total of 798 10th grade students were surveyed in mainland China. The results showed that (1) male students performed better than female students in STEM career expectations, STEM value beliefs, STEM self‐efficacy beliefs, as well as parents' and teachers' support; (2) female students' STEM career expectations could be predicted by parental support, STEM value beliefs, and STEM interest beliefs, while male students' STEM career expectations were positively influenced by parental support, STEM self‐efficacy, and STEM interest beliefs. Hence, there were apparent gender differences regarding STEM interest beliefs, STEM self‐efficacy and their relationship toward future career expectations. Specifically, STEM interest beliefs were positively correlated with STEM career expectations of female students, whereas STEM self‐efficacy could only significantly influence male students' STEM career expectations.