The work aims to study the problem of the effect of multiple micro-cracks on the kinked macro-crack by a theoretical method. In this paper, the mechanical behavior of the kinked macro-crack tip and the effect of multiple micro-cracks on the kinked macro-crack propagation angle and the closed regions of the kinked macro-crack were analyzed mainly. The obtained results will provide a theoretical basis for practical engineering applications. When solving the problem studied in this paper through theoretical analysis, it was divided into two steps. Firstly, the problem considered in this paper was divided into two sub-problems based on the superposition principle, and then solved one by one. Secondly, the first sub-problem was solved by material mechanics and the second sub-problem was solved by the distributed dislocation technique. Further, a singular integral equation about the dislocation density function was established. The singularity problem of the dislocation density equation was solved based on the Gauss-Chebyshev integration method and the numerical solution of the equation was obtained by means of computer programming. Finally, a series of valuable mechanical parameters about the kinked macro-crack were obtained. In this paper, some results were obtained which will provide a theoretical basis for practical engineering applications. For example, the stress field near the kinked macro-crack and the related mechanical parameters of the macro-crack tip were obtained. Specifically, these mechanical parameters affected the micro-crack length and the number of micro-cracks on the stress intensity factor at the tip of the macro-crack. The closed regions of the macro-crack with different kinked angles, and the effect of the orientation of micro-cracks and the number of micro-cracks on the propagation angle of the kinked macro-crack were analyzed. Several practical conclusions were obtained in this paper. It is concluded that the regions near the kinked macro-crack surface has a shielding effect on the tensile stress, which will lead to stress relaxation of the tensile stress near the crack surface. The regions near the crack tip will amplify the tensile stress. In other words, the stress will be concentrated near the crack tip, and the kinked macro-crack tip will further propagate as the increased of the applied load. When only one micro-crack is located at the macro-crack tip about –30°<θ<50°, the stress intensity factor at the kinked macro-crack tip will increase, which will promote the propagation of the macro-crack. When the micro-crack is located at 50°<θ<90° or –90°<θ<–30°, the stress intensity factor at the tip of the macro-crack will decrease, which will inhibit the propagation of the macro-crack. The stress intensity factor at the tip of the macro-crack will become larger with the increase of the micro-crack length, and decrease with the increase of the distance between the micro-crack and the macro-crack.