The conglomerate is characterized by multiscale grain packing structure and various pore distribution morphology, which is also named as multimodal structure. However, artificial conglomerate applying the experimental investigation differs significantly from natural conglomerates in terms of pore structure, due to centralized pore distribution and lack of nano-scale pores. Hence, we present an experimental method for controlling the pore structure in the artificial conglomerate. First of all, Portland cement was adopted as the main cementing agent, which could generate wider pore distribution and more proportion of nano-scale pores. Next, the grain size distribution design model was applied to realize the various pore structure. Finally, Genetic Programing was adopted to quantify the relationship between grain size distribution and pore structure. The results demonstrated that grain size distribution is composed of coarse grain peak (CGP) and fine grain peak (FGP), various morphology of grain distribution could be realized by adjusting the width and granularity of CGP and FGP. Moreover, lithology is determined by the average value μ1 of CGP, while permeability is determined by the average value μ2 of FGP. As the granularity difference between CGP and FGP performs larger, the morphology of pore distribution transforms from steep peak to hills in the conglomerate, most frequent and average radius of pore decrease, and capillary curve morphology transforms from concave to convex. In comparison with natural cores within alluvial fan of Karamay conglomerate reservoir, pore distribution morphology of artificial conglomerates has high similarity with natural cores.