Abstract: The paper studies the properties of bulb and web plates of two D36 bulb flat steels. The relationship between the properties and microstructure and difference in property of the two bulb steels were analyzed based on microstructure observation under metallographic and TEM. The results show that two steels have fine microstructure and good strength as well as toughness.The dislocations in the steel increase the strength of the steel obviously, and combining with the low sulfur and phosphors composition controlling, the low carbon bulb steel can be produced with higher strength and better toughness.