By Karamata regular varying theory, a perturbed argument and constructing comparison functions, we show the exact asymptotic behaviour of the unique solution u ∈ C 2 (Ω) ∩ C(Ω) near the boundary to a singular Dirichlet problem − u = b(x)g(u) + λf (u), u > 0, x ∈ Ω, u| ∂Ω = 0, which is independent on λf (u), and we also show the existence and uniqueness of solutions to the problem, where Ω is a bounded domain with smooth boundary in R N , λ > 0, g ∈ C 1 ((0, ∞), (0, ∞)) and there exists γ > 1 such that lim t→0 + g (ξ t), the function f (s) s+s 0 is decreasing on (0, ∞) for some s 0 > 0, and b is nonnegative nontrivial on Ω, which may be vanishing on the boundary.