The　depth　to　groundwater　table　(DGT)　and　the　stability　sites　of　groundwater　were　closely　related　parameters　in　groundwater　research.　Controlling　the　DGT　and　identifying　stability　sites　of　DGT　were　of　great　significance　to　prevent　soil　salinization　and　improve　groundwater　monitoring.　In　this　study,　using　DGT　data　from　the　Hetao　Irrigation　District　(HID)　from　1991　to　2015,　combined　with　spatial　interpolation　and　coefficient-of-variation　methods,　this　study　explored　the　spatiotemporal　variation　characteristics　and　scale-effect　problems　of　DGT　from　four　hierarchical　scales:　the　irrigation　district,　irrigation　subdistrict,　main　canal,　and　branch　canal.　The　Spearman　correlation　coefficient,　average　relative　difference,　and　standard　deviation　were　also　used　to　further　clarify　the　characteristics　of　groundwater　time　stability　and　its　periodic　variation　rule.　The　results　indicated　that　the　spatiotemporal　variation　in　DGT　in　the　HID,　and　showed　moderate　variation　characteristics,　consistent　with　scale-effect　features,　which　was　deeply　influenced　by　the　regional　climate　and　human　activities.　The　DGT　in　the　HID　showed　different　temporal　stabilities　before　and　after　2000　caused　by　the　application　of　Water-saving　practices　(WSPs).　The　stability　sites　were　not　entirely　the　same　in　different　years　or　time　periods,　but　they　were　all　at　the　moderate　DGT　level　in　the　HID.　The　results　of　this　study　can　provide　more　insights　for　improving　soil　salinization　and　groundwater　monitoring　and　provide　more　information　for　agricultural　water-use　efficiency　and　management.