The present research examines analytically and experimentally the mode-I and mode-II and mixed mode-Interlaminar fracture toughness of PAN based carbon/epoxy composite. A modified Arcan fixture, well-suited for the study of the behavior of used composite assemblies, was developed in order to focus on the analysis of the fracture behavior of the material. The edge effects are minimized by using an appropriate design of the substrates so that experimental results give reliable data. Also the mode-I and mode-II stress intensity factors were computed for different crack lengths and load orientation angles using finite element analysis. The numerical results show that the modified Arcan specimen is able to provide pure mode-I, pure mode-II and any mixed mode loading conditions. It is shown that the results obtained from the fracture tests are consistent very well with mixed mode fracture theories. Obtained results indicated that fracture toughness and stress intensity factor for sliding mode enhanced up when the loading angle increased. Mechanism of fracture and toughening were examined by using scanning electron microscopy.