Abstract: In order to realize the three-dimensional physical simulation experiment of loose sandstone reservoirs, one of the key points lies in how to obtain the three-dimensional large-size cores that can represent the actual reservoir conditions. However, due to the characteristics of small cementation strength, easy to loose, the large-scale cores drilling on site are difficult to achieve, so the preparation of weakly cemented three-dimensional large-scale loose sandstone cores is proposed. Through the design of the core mold, based on the particle size group and physical parameters of the target reservoir, and considering the macroscopic characteristics such as the actual reservoir thickness and the shale interlayer, weakly cemented three-dimensional large-scale core and saturated probe core are used. The physical properties of formed cores are evaluated and tested. The results show that compared with the actual reservoir, the porosity and permeability error of the core model is kept at about 10%, the precision is high, the homogeneity in the layer is good, the average cementation index of each layer is 1.6, which is a weak cementation category, and the degree of cementation consistent with the target reservoir. The prepared core can be done well in reducing the physical properties and macroscopic structure of the actual reservoir, and provides reliable core source support for the three-dimensional physical simulation experiment of the loose sandstone reservoir.