When calculating the earth pressure of the retaining wall, it is usually considered that the earth pressure at the nook of the retaining wall is different from that of the long straight wall. The earth pressure at the nook is calculated separately with the earth pressure of the circular retaining wall. This study proposes a method for calculating the earth pressure of the circular retaining wall as a whole. Based on the Coulomb earth pressure theory, the limit equilibrium theory is used to calculate the rupture angle of the sliding soil behind the retaining wall. Then calculus is used to calculate the resultant force of the earth pressure along the symmetry line of the wall, which can consider the friction between the wall back and the backfill at the same time. The results show that the active earth pressure and the rupture angle of the circular retaining wall decrease with the increase of the friction angle of the soil wall. This calculation method can provide a reference for the earth pressure calculation of the actual retaining wall engineering.