Abstract: Adopting the method of arrangement analysis,this paper divides the general economic benefit system of water conservancy project into flood-control,power-generation and irrigation benefits subsystems,identifying their respective risk factors,establishing a risk analysis model of economic benefit based on the maximum entropy principle,and presenting the solving method.The paper analyzes the risk of general economic benefits in two ways : one way is to obtain the maximum entropy density function of the total benefit indices through a direct probability analysis of the identified factors of the system; the other way is to analyze the probability characteristic of subsystem benefit in advance,then combines the risks to examine the probability nature of the general system according to the idea of "risk tree".Finally,a practical example is provided to testify the feasibility and practicality of the model.