Under the influence of climate change and rapid economic and social development, the contradiction between water consumption and ecological environment is becoming increasingly prominent, and ensuring the ecological flow of rivers and lakes is of great significance. Due to the lack of long-term hydrological data, there is relatively little research on the ecological flow guarantee of small and medium-sized rivers. However, the demand for ecological flow guarantee for ecological environment health is increasing. Therefore, conducting research on the ecological water level（flow）of rivers and lakes without long-term data is of great practical significance. This article takes the Lianyang river as the research object to clarify the ecological water level（flow）control section, sort out appropriate calculation methods,scientifically determine the ecological water level （flow） guarantee goals, and propose ecological water level（flow）guarantee measures. The study can provide scientific support for the ecological water level （flow） guarantee in the Lianyang river basin, and also provide reference for the determination of ecological flow indicators in rivers lacking long-term hydrological data.