During the COVID-19 pandemic, many teachers reconsidered their attitudes to-ward online learning. According to surveys, they will combine online educational materials and face-to-face classroom practices. Blended learning in mathematics education provides personalized learning, alternative methods for teacher-student feedback and communication. In addition, mathematics teachers get the opportunity to make extensive use of 3D graphics technologies, AR applications, dynamic geometry environments for visualization. Our goal is an empirical study of the conditions for improving the effectiveness of teaching stereometry in high school through the use of visualization technologies and blended learning. Our re-search confirmed that after forced distance learning in the COVID-19 pandemic there has been a positive change in the attitude of math teachers towards blended learning, and that high school students are ready for blended learning. A blended learning model for geometry was proposed, a feature of which is that the content of the digital learning environment is based on the principles of visualization, and e-tools for visualization are actively used in teaching. The conducted research proved the success of the proposed model.