In this paper, an isogeometric analysis method is proposed to obtain the notch tip stress intensity factor for the plane fracture problem with V-notch. Based on the isogeometric analysis, which discretizes the overall structure and constructs the stiffness matrix of the structure, obtains the equilibrium equation, and simultaneously obtains the coordinate information of the nodes. Combined with the displacement expression of the plane with sharp notch in polar coordinate system, the node coordinate information of the whole field is substituted into the analytical expression after coordinate conversion to obtain a transformation matrix, and the isogeometric equilibrium equation is converted into a smaller-dimensional equation. The coefficients of the analytical solution of the displacement field can be calculated, and the stress field and the stress intensity factor of the notch are obtained at the same time. This method unifies numerical modeling and numerical calculation into one platform, which improves the efficiency of numerical analysis; avoids the grid-sensitive problem of iso-geometric analysis fracture problems, and the stress intensity factors can be directly solved without any post-processing program, and avoids the problem of inconsistency in the calculation of isogeometric equations.