In order to analyze the factors influencing sandstone mechanical compaction and its physical property evolution during compaction processes, simulation experiments on sandstone mechanical compaction were carried out with a self-designed diagenetic simulation system. The experimental materials were modern sediments from different sources, and the experiments were conducted under high temperature and high pressure. Results of the experiments show a binary function relation between primary porosity and mean size as well as sorting. With increasing overburden pressure during mechanical compaction, the evolution of porosity and permeability can be divided into rapid compaction at an early stage and slow compaction at a late stage, and the dividing pressure value of the two stages is about 12 MPa and the corresponding depth is about 600 m. In the slow compaction stage, there is a good exponential relationship between porosity and overburden pressure, while a good power function relationship exists between permeability and overburden pressure. There is also a good exponential relationship between porosity and permeability. The influence of particle size on sandstone mechanical compaction is mainly reflected in the slow compaction stage, and the influence of sorting is mainly reflected in the rapid compaction stage. Abnormally high pressure effectively inhibits sandstone mechanical compaction, and its control on sandstone mechanical compaction is stronger than that of particle size and sorting. The influence of burial time on sandstone mechanical compaction is mainly in the slow compaction stage, and the porosity reduction caused by compaction is mainly controlled by average particle size.