Land use/cover change (LUCC) exerts a decisive impact on ecosystem problems. Over the past 40 years of China's reform and opening up, the development and exploitation of land resources have been made to the greatest extent, and economy and society have achieved considerable growth; however, it is also facing serious ecological security (ES) problems. The rapid change of land use caused by human activities has posed a menace to the ES. It is significant for the evaluation and protection of the regional ecological environment to combine LUCC and ES evaluation by predicting the change of land use and simulating ES model. As the main platform to promote the integration of the Yangtze River Delta, Zhejiang Greater Bay Area faces the pressure of rapid population growth and resource consumption. How to maintain and improve the integrity of the regional ecosystem is very important for the sustainable development of the region. Zhejiang Greater Bay Area was selected as the study area, ecological security evaluation index system was established based on land use types, CA-Markov model was adopted to predict the land use/cover change and simulate the ES pattern under three different scenarios in 2030. Forest land has always been the main land use type in Zhejiang Greater Bay Area, mainly concentrated in the continuous mountainous and hilly areas in Western and central and southern Zhejiang. Cultivated land is mainly distributed in Hangzhou-Jiaxing-Huzhou Plain, Ningshao plain and the estuary plain area along the lake, and the proportion of construction land is increasing continuously. The ES of Zhejiang Greater Bay Area in 2005, 2010, 2015 and 2018 was evaluated on the basis of the Pressure-State-Response (PSR) model. The proportion of areas with general security level or above increased from 58.83% to 60.02%, and then decreased to 59.42%. At the same time, by changing the transfer probability matrix of different land use/cover changes, three scenarios of inertial development, excessive expansion and ecological protection were set up. The results showed that the proportion of areas with ecological security at or above the general security level under the three scenarios were 58.61%, 57.60% and 58.46% respectively. The spatial distribution pattern of ES in Zhejiang Greater Bay Area was opposite to that of socio-economic data such as population density and GDP. The utilization rate of farmland in plain areas was high, while its ES level was low. The development level of ecological resources in hilly areas was low, while the ES level was high. This indicates that the ES level in areas with high urbanization level was relatively low, while the ES level in areas with good ecology was relatively high.