The　present　study　aims　at　preparing　lightweight　slag　based　geopolymer　(LW-SG)　and　studying　its　mechanical　properties　under　dynamic　and　quasi-static　loads.　Firstly,　three　LW-SG　with　different　densities　were　prepared　by　replacing　the　slag　with　expanded　perlite　(EP).　Secondly,　the　density,　wave　velocity　and　pore　structure　of　LW-SG　with　different　EP　contents　were　tested.　Thirdly,　the　mechanical　properties　under　quasi-static　and　dynamic　loads　were　compared.　Finally,　the　effects　of　the　strain　rate　and　EP　content　on　the　mechanical　properties　and　failure　modes　of　LW-SG　were　discussed.　The　results　showed　that　with　the　EP　contents　increase,　the　dry　density　and　longitudinal　wave　velocity　gradually　decreased,　while　the　porosity　increased.　In　addition,　the　quasi-static　compressive　strength　and　elastic　modulus　of　LW-SG　increased　with　curing　ages,　but　decreased　with　EP　contents　increased.　The　dynamic　compressive　strength,　dynamic　increase　factor,　strain　energy　density　and　damaged　degree　of　LW-SG　all　showed　an　increasing　tendency　with　the　strain　rates　increase,　which　exhibits　an　obvious　strain　rate　dependence.　Under　the　same　strain　rate,　the　dynamic　compressive　strength　and　strain　energy　density　decreased　with　the　EP　contents　increase,　while　the　damaged　degree　increased　with　the　EP　contents　increase.