Northwest Yunnan, historically a pivotal corridor for interactions among various ethnic groups from northern and southwestern China, played a significant role in prehistoric human migrations and the dissemination of agriculture. The Jicha site, located at the south end of the Hengduan Mountains in northwest Yunnan, is an important metallurgical site occupied during the period from the Late Neolithic to the Early Iron Age. Based on phytolith analysis of soil samples collected from this site, this study reveals that the inhabitants from 3800 to 2200 cal BP primarily subsisted on cultivated plants. Within the relatively stable agricultural system, rice remained the staple diet, complemented by dryland crops such as wheat, foxtail millet, and common millet. Among these crops, wheat appeared around 3500 cal BP and became the dominant dryland crop by the Middle to Late Bronze Age. Additionally, the inhabitants diversified their diet by utilizing plant resources effectively from the surrounding areas. The evidence indicates the ancestors had an advanced capacity to organize social labor and developed relatively mature skills for cultivation management and crop processing, which were related to large-scale grain harvesting and processing or storing in specific areas and possibly further strengthened rice cultivation.