In this present paper, we consider the following critical Kirchhoff problemwhere a, λ ∈ R and m, μ ∈ R + ∪ {0}, N ≥ 3 and 2 < p < 2 * . In this first part, a pure critical Kirchhoff problem (m = μ = 0) has been considered for both a > 0 and a ≤ 0. We obtain a series of fairly complete existence and multiplicity results and have a clear understand the solutions of this pure critical Kirchhoff problem. In particular, if N ≥ 5, a > 0 and λ > 0 is suitable small, we obtain two positive solutions, in which one is a mountain pass solution and another one is a global (local) minimum solution. In the second part, the original perturbation problem with m, μ > 0 has been considered and two positive solutions also have been obtained for N ≥ 5, which is rather different compared with the case that λ = 0.