Eucommia antifungal protein (EAFP) crystals can be easily grown into big crystals in several hours. By in situ atomic force microscopy (AFM) the dynamic topographic changes were observed on the surfaces of several EAFP crystals and growth rates were measured at different supersaturations of the protein solution. The results of AFM experiments indicated that growth rates of EAFP crystals were strongly and directly related to the supersaturations, in addition to the inherent structural rigidity and the interior stability of the molecule. At higher supersaturation (σ=1.78) the EAFP crystals grew very fast; at moderate supersaturation (σ=1.5) the growth rates were 12 nm/s and 24.2 nm/s along the crystallographic axes b, c of the {100} surface respectively, which were faster than that of lysozyme (6～7 nm/s). Even at lower supersaturation the EAFP crystals grew almost as fast as other protein crystals did. The effects of the concentration of precipitator on crystal growth observed on the crystal growth of AFM at lower supersaturation were also presented.