In historical masonry structures having vault, dome and high walls, for safety against gravity, wind and earthquake loads, buttresses are crucial elements. This study aims to investigate the effect of buttress form on the transverse seismic resistance of high masonry walls. For this purpose, a real historical masonry structure covered by a barrel vault, and has a simple and regular plan and elevation shape was considered. From a slice of this structure, a calculation model and a basic model were created. For the masonry, macro-modelling approach was used. Nonlinear static analysis method was adopted, and finite element modeling and calculations were carried out using the Abaqus program. Firstly, on the calculation model the effect of buttress depth on transverse seismic resistance was investigated, and it was seen that the resistance is almost linearly related to the buttress depth. Then, two groups of analyses were performed on the models obtained by mounting different buttress forms to the basic model. In the first group, the volumes of the buttresses were kept equal, and in the second group their base depths and thicknesses were taken equally. At the end of these analyses, by comparing the base shear forces obtained for the models, the effectiveness of buttress form on the transverse seismic resistance has been determined and evaluated. The results revealed that the model with curvilinear concave buttresses in the first group analyses and the model with semi-cylindrical buttresses in the second group analyses have the highest seismic resistance.