Abstract: Carbon black (CB)/polycarbonate (PC) conductive composites was synthesized by in-situ polymerization method, during which CB could be dispersed more easily and more uniformly in PC with lower viscosity. Moreover, the catalyst loaded on CB also plays the role of the coupling agent to help CB better dispersing. Compared with the conventional melt blending method, CB/PC conductive composites synthesized by in-situ polymerization method have lower percolation threshold, and the volume resistivity of the composite with 4.32% mass fraction of CB is 1.56×10⁶ Ω·mm. SEM shows that CB in the samples synthesized by in-situ method is mixed more completely, and forms conductive network more effectively.The logarithm of the positive temperature coefficient (PTC) of the CB/PC sample obtained by in-situ method is 4.69. CB/PC conductive composites have the potential as self-temperature control material.