Abstract： A predator-prey system with Holling-Ⅳ functional response is investi-gated. The qualitative analysis for the model indicates that the positive solutions of the system are all bounded, thus, when the equilibrium is unstable, the system has at least one stable limit cycle. By using the method of formal power series of Poincaré, we get a result that the positive equilibrium is a stable fine-focus of order at most 2. Moreover,base on the theory of Hopf bifurcation, we obtain that the system at least has two limit cycles under certain conditions.