To　explore　the　effects　of　different　alkalinity　substances　(Na2CO3,　KHCO3,　NaHCO3)　and　concentration　ranges　(2000,　3000,　4000mg/L　(as　CaCO3))　on　the　middle-temperature　anaerobic　digestion　system,　a　static　batch　semi-continuous　stirred　tank　was　used　in　the　experiment.　The　comprehensive　reactor　operation　and　microbial　high-throughput　sequencing　analysis　showed　that　Na2CO3　could　promote　the　hydrolysis　and　acidification　process　in　three　different　types　of　alkalinity,　while　NaHCO3　was　more　prominent　in　gas　production　and　reduction.　It　indicated　that　Na2CO3　was　more　likely　to　promote　hydrolysis　and　acidification　in　the　limiting　stage　compared　to　other　samples,　when　the　alkalinity　of　the　system　was　adjusted.　Under　different　concentrations,　the　hydrolysis　capacity　was　enhanced　by　increasing　the　concentration　of　added　basicity,　which　led　to　the　deterioration　of　the　dehydration　performance,　while　the　Volatile　Fatty　Acids　changed　little,　and　the　excess　basicity　will　reduce　the　gas　production　and　reduction　of　the　system.　©　2019,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.