Since student teachers' emotions during field experiences are highly relevant to their overall learning and professional development, they are worthy of closer investigation. Thus, based on longitudinal data and co-occurrence network analyses, this study determines whether and how often positive and negative emotions co-occur among a sample of student teachers at three different timepoints (beginning, middle, and end) of a 15-week field experience. The findings revealed that a significant number of student teachers experienced mixed emotions, with the frequent co-occurrence of feeling stressed alongside positive emotions such as interest, attentiveness, excitement, strength, and confidence. Moreover, the proportion and structure of emotional co-occurrences changed over time. Notably, the prevalence of mixed emotions was higher in the initial and middle stages of the field experiences. These findings highlight the limitations of conventional correlation analyses in capturing important emotional information. The implications of these insights for student teacher support and development are discussed.