With the background of slopes with building loads in karst areas, wherethe building loads are to be simplified as loads on the top, and based on similar material theory, a similar material plane strain model of double karst caves has been built, with double caves laid out from top to bottom, and a three-stage load procedure has been proposed for the preloading, simulation of slope excavation and an overloading involving slope collapse. A research has been carried out on the roof deflection(RD) of karst caves, as well as the horizontal displacement in the middle of sidewall close to the slope surface (HDMS) of double caves, the rock pressure (RP) and the horizontal displacement of layered slope surface (HDLS) formed by excavation. The research results show that: in the whole process, RD shows an increasing trend, especially with a dramatic increase at the third stage; at the first stage, HDMS show a slowly-increasing trend, with a sharp fluctuation with HDMS at the top cave at the second stage, and with a constant sharp increase with HDMS of the bottom cave at the third stage. HDMS of the top cave rises rapidly and then drops quickly, whereas HDMS of the bottom cave exhibits little change.Rock pressure (RP) is increased in the whole test process,with a more remarkable increase close to the slope surface; at the first and second stages, a slow increase trend of HDLS is exhibited in a similar parabolic form; and at the third stage, HDLS increases markedly, showing an extrusion effect at the bottom of the slope surfaceat the third stage.