A priori estimate Positive stationary solution a b s t r a c tIn this paper, we are concerned with the positive solution set of the following quasilinear elliptic systemwhere Ω is a bounded smooth domain in R N , α, β, γ are nonnegative constants, a, c, d, m are positive constants, b is a real constant. This elliptic system is the stationary problem of a predator-prey model, in which u and v denote the population densities of the prey and predator, respectively. Regarding b as the bifurcation parameter, the global bifurcation structure of the positive solution set is shown. Then the nonlinear effect of either large α or β on the bifurcation point is deduced. Moreover, as α is large, we show that the positive solution set is only of one type, whereas, as β is large, the positive solution set is of two types. Additionally, in certain circumstances, we also show that which one of the two types can characterize the positive solution set.