In view of the shortcomings of the current research on the response mechanism of ecosystem services value to urban and rural construction land expansion, By taking the three outlets of southern Jingjiang River as the research object, this study calculates the ecosystem service value of the three outlets of southern Jingjiang River by equivalent factor method, analyzes the temporal and spatial variation characteristics of ecosystem service value, and analyzes the response mechanism of ecosystem service value to urban and rural construction land expansion by linear regression method. The results show that from 1990 to 2018, ESV in the three outlets of southern Jingjiang River increased from 44.356 billion yuan to 47.103 billion yuan, which experienced a gentle growth process as a whole. The spatial difference of ESV was obvious. Specifically, the area of the high- and medium-value areas decreased rapidly, and the area of the low-value areas increased rapidly. The expansion of construction land was more significant, with a total expansion of 27.74 km², which experienced the fluctuating expansion process of "slow-negative-slow-rapid- decelerated expansion". Construction land occupied different types of land, which has different degrees of impact on the loss and gain values of all kinds of ecosystem services, and the greater the proportion of occupation high ecological value land (water area, wetland), the higher the damage to the ecology. In the future use of the land of the three outlets of southern Jingjiang River, the traditional expansion mode of construction land should be changed, the boundary of urban land use should be reasonably planned, the red line of arable land should be strictly observed, and the level of intensive land use should be improved. At the same time, we should improve the management system of rivers and lakes, make more efforts on the ecological protection and restoration of rivers and lakes, and improve the ecological service function for rivers and lakes.