We consider the Ricci flow on CP n blown-up at one point starting with any U (n)invariant Kähler metric. It is proved in [31,9,21] that the Kähler-Ricci flow must develop Type I singularities. We show that if the total volume does not go to zero at the singular time, then any Type I parabolic blow-up limit of the Ricci flow along the exceptional divisor is the unique U (n)-complete shrinking Kähler-Ricci soliton on C n blown-up at one point. This establishes the conjecture of Feldman-Ilmanen-Knopf [8].It is proved in [13,7] that if the Ricci flow develops type I singularity on a closed manifold, then the type I blow-up limit along essential singularities must be a nontrivial complete shrinking Ricci soliton.CP n blown-up at one point is in fact a CP 1 bundle over CP n−1 given byLet D 0 be the exceptional divisor of X defined by the image of the section (1, 0) of O CP n−1 ⊕ O CP n−1 (−1) and D ∞ be the divisor of X defined by the image of the section (0, 1) of O CP n−1 ⊕ It is proved by Feldman-Ilmanen-Knopf [8]) that there exists a unique U (n) invariant complete Kähler-Ricci gradient shrinking soliton on C n blown-up at one point (FIK soliton) and they further made the following conjecture.Conjecture 1.1. Let g(t) be the U (n) invariant metrics satisfying the Kähler-Ricci flow on X = CP n blown-up at one point for t ∈ [0, T ). Let T ∈ (0, ∞) be the singular time and lim inf t→T − V ol(X, g(t)) > 0.Then the flow develops type I singularities and any type I parabolic blow-up limit of g(t) with a fixed base point in the exceptional divisor E is the unique FIK soliton on C n blown-up at one point.This conjecture was partially established by Maximo ([12]) when the dimension n = 2 under certain open conditions on the initial metric. Our main result in this paper is to show that in the non-collapsed case, the blow-up limit of the Kähler Ricci flow is biholomorphic to C n blown-up at one point and the limit Kähler Ricci soliton is the FIK soliton constructed in [8] on C n blown-up at one point, hence establishing Conjecture 1.1. Our main theorem is Theorem 1.2. Let X be CP n blown-up at one point and E be the exceptional divisor. Let g(t) be the U (n)-invariant solution to (1.1) on X on [0, T ). If lim inf