Entrepreneurial opportunity identification is a prerequisite for entrepreneurship. It is a cognitive process formed by the interaction of many factors, of which entrepreneurial alertness is one of the most critical. However, the mechanism of how previous experience affects entrepreneurial alertness and how it further influences entrepreneurial opportunity identification still remains unclear. Based on previous research, this study is designed to reveal the transition path between previous experience and farmers’ identification of entrepreneurial opportunity, as well as the intermediate role which entrepreneurial alertness plays in this process. A theoretical model of relationship between “previous experience－entrepreneurial alertness－entrepreneurial opportunity identification” was constructed by employing entrepreneurial alertness as an intermediate variable. Moreover, empirical studies were conducted on farmers who intend to start new businesses. The results show that a direct interaction between previous experience and opportunity identification does not always exist. Part of these two are embedded in the cognitive sphere, influencing opportunity identification through improving entrepreneurial alertness. Additionally, in its interactions with different previous experiences and entrepreneurial opportunity identification, entrepreneurial alertness displays different characteristics as follows: First, entrepreneurial alertness plays an intermediate role in the positive relationship between previous experience and entrepreneurial opportunity identification. Previous working experience has a direct influence on entrepreneurial opportunity identification. Rich working experiences are helpful to the improvement of farmers’ ability to properly evaluate information and identify the entrepreneurial opportunities that would be regarded as potential threats or risks by others. In addition, previous working experience affects farmers’ entrepreneurial alertness, which indirectly influences opportunity identification. Second, the intermediate role of entrepreneurial alertness between previous entrepreneurial experience and entrepreneurial opportunity identification was not verified in this study due to the limited sample size. Further study is needed to explore its intermediate role. Last, entrepreneurial alertness plays an intermediary role in the positive relationship between previous training and entrepreneurial opportunity identification. Previous training experience has a direct effect on opportunity identification. Training will greatly increase farmers’ stock of knowledge and improve their cognitive level, which will help them identify entrepreneurial opportunities. In addition, it sharpens their entrepreneurial alertness, indirectly improving their ability to identify entrepreneurial opportunities. This study has significant implications for farmers’ entrepreneurial practice and for government policy making: (1) Farmers may seek employment before starting their own businesses. They can try different jobs to accumulate knowledge and experience, and to develop their cognitive abilities and entrepreneurial alertness, which will improve their ability to identify entrepreneurial opportunities. (2) The government should increase its support for the training of farmers so as to improve their ability to identify such opportunities.