The interaction effects between a single circular interfacial crack and screw dislocation located inside the matrix were investigated for 1D hexagonal quasicrystal. Through applying the complex potential method, the closed form solutions of this problem were obtained. The degradation results are consistent with the conclusions in previous literature. The stress intensity factor at the crack tip was also derived. The results show that the stress intensity factor decreases with the increase of the distance between the dislocation and interfacial crack. With the increase of the opening angle of the circular interfacial crack, the stress intensity factor increases firstly and then decreases.