The invention relates to a system and method for detecting plant diseases based on near field acoustic holography technology. According to acoustic emission phenomena of plants and on the theoretical basis of the near field acoustic holography technology of a distributed source boundary point method, a cylindrical surface-spherical surface non-conformal-surface acoustic holography experiment model is established, and simulation experiments on single sound sources and double sound sources are respectively carried out. By changing of parameters, in the model, such as the holographic cylindrical surface radius, holographic measuring point number, and node number on reconstruction spherical surface, distance between fictive particular solution sources and nodes on the reconstruction spherical surface, and the like, feasible experimental parameters are obtained. Simulation results show that the method can accurately identify and locate the position of an acoustic emission source. On the basis of the experimental parameters, a signal acquisition acoustic holography experiment system which adopts DSP as a core is established, and data analysis and processing are carried out by an upper computer which adopts Labview as a software platform. The system and method for detecting plant diseases based on the near field acoustic holography technology adopt plant acoustic emission signals as important sensitive information to know the growth states and disease-affected situations of the plants, and through studies of the acoustic emission signals based on the near field acoustic holography technology of the distributed source boundary point method, the diseases can be timely discovered and identified, and a new way and the new method for the prevention and control and detection of the plant diseases is provided.