In response to the problem of poor seismic performance of existing brick masonry buildings in urban areas, a new seismic reinforcement technology suitable for multi-layer brick masonry buildings is proposed, which uses vertical unbonded prestressed steel bars to reinforce the masonry walls, thereby improving the seismic performance of the walls and enhancing the overall seismic capacity of the buildings. In order to understand the reinforcement effect of this technology, two batches of 17 wall components were subjected to pseudo static test research, and a two story full scale house model was subjected to pseudo dynamic test research. The experimental research results of wall components indicate that this reinforcement technology can significantly improve the crack resistance, shear bearing capacity, and ductility of brick masonry walls. The pseudo dynamic experimental study of the building model further indicates that after using this technology for reinforcement, buildings with seismic fortification intensity less than 8 degrees remain elastic under the pseudo dynamic action of simulating rare 9 degree earthquakes, and their seismic resistance is significantly improved. On the basis of experimental research, a calculation method for the shear bearing capacity of prestressed reinforced masonry walls was proposed. The actual application of this technology in a multi-storey office building in Huairou District of Beijing shows that it has the advantages of simple construction technology, short construction period and low cost