Pyrene-based conjugated microporous polymers (CMPs) have been shown to exhibit significant microporosity and strong luminescence, but their structures are not well understood due to their insolubility and amorphous nature. Here, a series of pyrene-based CMPs with varying monomer compositions is studies using molecular simulations. The results are in good agreement with available experimental BET surface areas and powder X-ray diffraction data. As the monomer composition is adjusted to increase the degree of cross-linking, greater porosity is formed. Additionally, with high cross-linking degrees, the formation of 3-, 4-, 5-, and 6-monomer rings are found to be more prevalent. The increase in strained rings within the network structures correlates with shifts in optical spectra due to the increased conjugation. Together with experimental and other computational results, the simulations here enable better understanding of the structure-property relationships in pyrene-based CMPs.