This paper presents the experimental result of K-shell ionization probability over 2.52 MeV p-wave narrow resonance in the reaction of 56Fe(P, P0)56Fe. The 50% modification of KX-ray emission probability on resonance relative to off resonance has been clearly observed. It indicates that with the ratio UK/Γ as large as 5.3, the interference between the incoming and outgoing target K-shell ionization amplitudes in an atomic collision still exists. From the comparison of calculation based on theoretical formula of Blair and Anholt with the experimental result. The imaginary part of the atomic monopole amplitude Imb0 was deduced and the R0=Imb0/Reb0 was obtained as +1.8.