Abstarct: Abstract Strength is one of the most important issues in the design of engineering structures. Preventing structural failure in areas of discontinuity has been the focus of engineers. In recent years, the use of anisotropic materials, especially in the form of thin sheets and shells, has developed a lot. Cracks are caused by factors such as fatigue and low strength of the material. The presence of cracks or quasi-cracks can significantly reduce the strength of the part or structure and is dangerous, so it is important to estimate the static strength and growth of cracks, fatigue and ultimate failure. In this research, an orthotropic quasi-infinite plate with an oval opening with two equal cracks under uniform heat flux is investigated. Numerical calculations are performed by the mixed variable method. Simulation is done in the software and the necessary checks are performed. The effect of the rotation angle of the opening on the stress distribution is investigated and the stress intensity coefficients are obtained for different crack lengths and the plate is investigated in two cases of boundary conditions in Abacus software. As the heat flux passes through the plate, the stress around the crack increases and reaches a maximum at the tip of the crack, and failure is predicted to start from that point. In the design, the openings that are created in the structures must be paid great attention to prevent accidents.