Based on the current situation of ecological environment of agriculture in Tianjin City, we divide the ecological service function of urban modern agriculture in Tianjin City into seven types: air regulation, climate regulation, water conservation, soil formation and protection, waste disposal, biodiversity conservation, and ecological entertainment. According to the method for assessing the value of natural ecosystem, coupled with the ecological service value equivalency factor table of China's ecosystem formulated by domestic scholars, we estimate the ecological value in Tianjin City. The results show that the actual ecological value of agriculture in Tianjin City was 30.752 billion yuan in 2010, close to the agricultural economic value (31.733 billion yuan) in 2010. Finally we put forth the following countermeasures for the ecological function development of urban modern agriculture in Tianjin City: strictly protecting arable land, and raising the standards of compensation for agricultural land requisition; actively and prudently developing facility agriculture, and preventing the blind scale expansion of facility agriculture to better give play to its ecological function; strengthening the construction of ecological agriculture, and promoting the market conversion of the ecological service value of agriculture; improving the environment, to form relatively complete agro-ecological system.