The Yiluo River Basin is located in the Central plains of China, an area commonly known as the center of origin of ancient Chinese civilization. Agriculture lays the foundation for social and economic development and triggers societal change and archaeobotany can provide important clues on this issue. archaeobotanical study is an important perspective on the relationship between agriculture and society development. However, relatively few archaeobotanical studies have been conducted in the Yiluo River basin, and the paucity of data has hindered our understanding of the relationship between agriculture and society. Therefore, the archaeobotanical analysis at the Suyang site in the middle reach of the Luo River provides an opportunity to understand how and why agriculture and society developed. Our analytical results of carbonized plant remains and phytolith, coupled with radiocarbon dating, showed that millet was the main crop in the late Yangshao culture (5,500–5000 BP), followed by rice. However, rice cultivation in the area expanded during the Longshan culture (5,000–4000 BP), and its importance as a crop possibly exceeded millet at Suyang. From the late Yangshao to Longshan, rice was cultivated in wet fields by utilizing the Luo River floodplain on a large scale. The proportion of rice at Suyang is the highest among contemporary sites in the Central Plains. It may be related to many reasons such as suitable environmental and geomorphological conditions, advanced water management, the influence of the Qujialing culture, and population growth. In the late Yangshao culture, crop processing seemed to have been concentrated in communal areas. However, during the Longshan culture, different steps of crop processing were scattered throughout the site. This change is hypothesized as a change in the family structure and economic production. After the Yangshao period, the nuclear family became the fundamental unit for social, cultural, and economic production in the Central Plains.