The purpose of this study was to investigate the effects of different particle sizes and contents of limestone powder (LSP) on the compressive strength and workability of ordinary Portland cement (OPC) paste. Three types of LSP with different specific surface areas (SSA) were used to replace OPC in proportions ranging from 0 to 40%. Both compressive strength and flow experiments were conducted, and the results were analyzed using regression analysis. The findings were further corroborated by X-ray diffraction analysis. The experimental results show that the higher the SSA and the smaller the particle size, the worse the workability. Notably, when the content of LSP is less than 20%, the influence of LSP particle size on compressive strength and workability is not significant. However, when it exceeds 20%, the greater the SSA of LSP, the smaller the particle size, and the smaller the reduction in compressive strength. According to the result, the LSP-F has the optimal performance in the higher replacement, especially at the 20% replacement.