Abstract: Water resources security is closely related to agricultural security. Beijing is a city with serious shortage of water resources. Under the restriction of water resources, the scale of agriculture has been shrinking, while it highlighted the problem of agricultural security. Ecological security of water resources and agricultural security in Beijing were evaluated by using a "pressure-state-response" model in this paper, and the results showed that the Beijing agricultural security level continued to decline over the past ten years, while the level of water resources security showed a trend of rising; the pressure and state of agricultural security showed a downward trend, but the level of response to agricultural security has steadily increased; the pressure and state of ecological security of water resources has synchronous fluctuation, and response ability of the ecological security of water resources overall increased. In order to improve the water resources of Beijing city ecological security and agricultural safety level, in addition to strictly controlling the total amount of population growth and water use, but also increasing the reuse of sewage treatment and collection and utilization of rainwater. Some strategies are necessary including implementing the strict farmland protection system, reducing the chemical fertilizer and pesticide pollution of water resources, increasing investment in agriculture and improving the comprehensive production capacity of agriculture, vigorously developing water-saving, ecological and circular agriculture.