The global COVID-19 pandemic has had an unexpected impact on all areas of human life and activity, including education. Schools are closed and the learning process is done online. All schools do not have adequate preparation to face the changes in the learning process. In such conditions, there are two important things to study, namely the principal's leadership function and teacher performance during and in the face of the Covid-19 pandemic with all its impacts, including the occurrence of learning loss. What kind of leadership function is carried out to overcome the decline in teacher performance that has an impact on the occurrence of learning loss and how do school principals carry out their roles as implementers of government policies in the field of education and as leaders of educational professionals.