Abstract: Analyzed here in the essay are the micro-structural properties of the as-hot-rolled and as-normalized X52NS acid-resistant linepipes as made of 14MnV and 14MnVTi steels. As a result，it is revealed that in the as-hot-rolled state，the 14MnVTi steel pipe containing Element Ti has finer grain size，which means that Ti plays a role in refining the grain，and that the yield strength slightly higher than that of the non-Ti 14MnV pipe；after the normalization treatment，the non-Ti 14MnV pipe has much finer grain size，and both of its tensile strength and impact energy value are higher than those of the Ti-containing steel pipe；due to the affinity of Ti and V are stronger than that of V，N in the steel first binds with Ti，and thus no more N remained to bind with V，which influences the composite precipitation strengthening effect. Therefore as for the X52NS acid-resistant linepipe，the overall mechanical properties of the 14MnV steel are better than those of the 14MnVTi steel.