The　study　aims　to　quantitatively　calculate　the　physical　and　chemical　effects　of　limestone　powder　(LP)　with　four　average　particle　sizes　and　two　amounts　in　cement　pastes　by　using　thermal　gravimetric　analysis　(TGA),　X-ray　diffraction　(XRD),　mercury　intrusion　porosimetry　(MIP)　techniques.　At　3d,　as　the　average　particle　size　of　LP　decreased　from　32　to　6　μm,　the　consumed　CaCO3　content　in　LP　increased　from　0.67%　to　1.71%,　and　the　chemically　reactive　portion　of　LP　increased　from　1.15%　to　2.95%.　However,　at　180d,　the　consumed　CaCO3　content　and　chemically　reactive　portion　of　LP　was　almost　2.4%　and　4.2%,　respectively.　At　3d,　as　the　LP　content　increased　from　25%　to　50%,　the　consumed　CaCO3　content　in　LP　increased　from　1.71%　to　2.02%,　and　the　chemically　reactive　portion　of　LP　increased　from　2.95%　to　3.5%.　However,　at　180d,　the　differences　of　consumed　CaCO3　content　and　chemically　reactive　portion　of　LP　between　cement　pastes　with　different　LP　content　were　limited.　The　physical　and　chemical　effects　of　limestone　powder　on　the　compressive　strength　of　cement　pastes　were　calculated.　At　180d,　as　the　average　particle　size　of　LP　decreased　from　32　to　6　μm,　the　contribution　of　chemical　effect　of　LP　on　the　compressive　strength　of　cement　pastes　increased　from　1.01%　to　1.08%　while　the　contribution　of　physical　effect　decreased　from　21.19%　to　20.03%.　©　2019