We study theoretically the quantum effects of the littlest Higgsmodel (LH) mediated by flavor changing one-loop Feynman diagrams onthe rare decay process t → cH0. The comparison of the decaywidth in the LH model with that in the standard model (SM) is made.We find that the decay branch ratio of t → cH0 in the LHmodel is at most of the order ∼10-12, which is two orderlarger than in the SM. The numerical results show that thedifference between the branch ratios in the LH model and the SM isgenerally sensitive to the LH model parameters, such as symmetrybreaking scale f, Higgs boson mass mH0, andx = v'4f/v2 in our chosen parameter space, butrelatively insensitive to the value choice of the cosine of themixing angle c and the ratio λ1/λ2.