The precipitates and hydrogen permeation behavior in three kinds of hot rolled low carbon heavy plate steels for enameling were analyzed; then, both sides of the steels were enameled. The experimental results show that a large amount of coarse Ti4C2S2 and fine Ti(C, N) particles exist in the optimized Ti-bearing steel, quite a lot of fine Ti(C, N) particles exist in the optimized carbon steel, but only a little bit fine Ti(C, N) particles exist in the carbon steel. The fishscaling resistance of the steels can be correlated to the effective hydrogen diffusion coefficient, and a model of correlation between the effective hydrogen diffusion coefficient and the volume fraction of the precipitates was established and verified. The effective hydrogen diffusion coefficient should be lower than 3. 96 x 10 6 cm2/s to avoid fishscaling in heavy plate steels.