In order to reduce the fracture accident of disc suspension insulators, the stress level of porcelain and the optimization of its structure were studied. The finite element model of the disc suspension insulator was established to investigate the stress distribution characteristics of the insulator under tension, and the stress on the porcelain under different tension directions was analyzed. The insulator structure was optimized based on finite element method and machine learning method. Results show that under the action of tension, the contact surface between porcelain and cement was partially separated, resulting in higher stress level on the middle wall of porcelain. The greater the angle between the tension direction and the axis of insulator was, the higher the stress level on the porcelain became. On the basis of finite element calculation, the machine learning method was adopted to optimize the structural parameters of the insulator, and the optimal structural parameters were obtained. The stress level of the optimal structure was reduced by 30% compared with that of the original structure. The finite element calculation of the optimal structure shows that the error rate was only 0.644%, indicating that the result is reliable and the optimization effect is significant. Therefore, in the process of cementing of insulator, the cementing strength should be enhanced. In the installation of insulator, the angle between the tension direction of the insulator and the axis should be minimized so as to effectively increase the working life of the insulator. The optimal parameters obtained by structural optimization can provide theoretical guidance and technical support for structural design.