Abstract: 780 MPa dual phase steels with two kinds of composition were produced under the same manufacturing condition; one had high carbon conent (carbon mass fraction of 0.157%, high-C series), and the other had low carbon content and was added with Nb and Mo elements (Nb-Mo series). The microstructure, tensile properties, hole expansion performance and nanoindentation hardness of hard and soft phases of the two steels were studied and compared. The results show that the microstructures of the two steels consisted of ferrite and martensite. Compared with those of the high-C series test steel, the ferrite grains of the Nb-Mo series test steel were refined, the yield strength and yield ratio were improved, and the hole expansion rate was higher. Due to the higher carbon content, the martensite in the high-C series test steel had relatively high hardness, and the hardness distribution was ralatively divergent. The hardness distribution of the martensite in the Nb-Mo series test steel was concentrated. The nanoindentation hardness difference between the ferrite and the martensite in the Nb-Mo series test steel was smaller, so the hole expansion performance was better.