Ground-source　heat　pump　(GSHP)　systems　with　medium-depth　and　deeply　buried　pipes　in　cold　regions　are　highly　important　for　addressing　global　climate　change　and　the　energy　crisis　because　of　their　efficient,　clean,　and　sustainable　energy　characteristics.　However,　unique　geological　conditions　in　cold　climates　pose　serious　challenges　to　the　heat　transfer　efficiency,　long-term　stability,　and　adaptability　of　systems.　This　study　comprehensively　analyses　the　effects　of　various　factors,　including　well　depth,　inner-to-outer　tube　diameter　ratios,　cementing　material,　the　thermal　conductivity　of　the　inner　tube,　the　flow　rate,　and　the　start-stop　ratio,　on　the　performance　of　a　medium-depth　coaxial　borehole　heat　exchanger.　Field　tests,　numerical　simulations,　and　sensitivity　analyses　are　combined　to　determine　the　full-cycle　thermal　performance　and　heat-transfer　properties　of　medium-depth　geological　formations　and　their　relationships　with　system　performance.　The　results　show　that　the　source　water　temperature　increases　by　approximately　4　degrees　C　and　that　the　heat　transfer　increases　by　50　kW　for　every　500　m　increase　in　well　depth.　The　optimization　of　the　inner　and　outer　pipe　diameter　ratios　effectively　improves　the　heat-exchange　efficiency,　and　a　larger　pipe　diameter　ratio　design　can　significantly　reduce　the　flow　resistance　and　improve　system　stability.　When　the　thermal　conductivity　of　the　cementing　cement　increases　from　1　W/(mK)　to　2　W/(mK),　the　outlet　water　temperature　at　the　source　side　increases　by　approximately　1　degrees　C,　and　the　heat　transfer　increases　by　13　kW.　However,　the　improvement　effect　of　further　increasing　the　thermal　conductivity　on　the　heat-exchange　efficiency　gradually　decreases.　When　the　flow　rate　is　0.7　m/s,　the　heat　transfer　is　stable　at　approximately　250　kW,　and　the　system　economy　and　heat-transfer　efficiency　reach　a　balance.　These　findings　provide　a　robust　scientific　basis　for　promoting　medium-deep　geothermal　energy　heating　systems　in　cold　regions　and　offer　valuable　references　for　the　green　and　low-carbon　transition　in　building　heating　systems.