In this paper, all-optical photonic crystal two bit adder based on nonlinear ring resonator is designed. The proposed structures includes threshold detectors and junctions. In our proposed structure, in order to resolve the low transmission problem in input junction, an enhanced junction is cascaded by a threshold detector to implement full adder cells. By cascading two optimized full adder a two bit adder has been designed. Nonlinear rods of the proposed structures are made of Silicon nanocrystal to create the required frequency shift for implementation of the proposed structures. In order to evaluate the performance of the proposed structures, the plane wave expansion and finite difference time domain methods are used. The proposed optimized full adder cell occupy an area about 340 µm2 with maximum power 5 W for switching mechanism. Our simulation results show that the proposed full adder can operate with a bit rate of more than 580 Gbits/s.