A　rapid,　high-resolution　and　effective　new　method　for　analyzing　12　diuretics　by　CE-ESI-MS　was　established　in　this　paper.　Ten　diuretics　(except　two　neutral　compounds)　could　be　fast　separated　by　CE　with　a　DAD　at　214　mn.　with　a　20　kV　voltage　within　6　min,　using　a　50　mu　m　id　and　48.5　cm　effective　length　uncoated　fused-silica　capillary　in　a　40　mM　ammonium　formate　buffer　(pH　9.40).　CE　was　coupled　to　the　mass　spectrometer　applying　an　orthogonal　electrospray　interface　with　a　triple-tube　sheath　liquid　arrangement.　The　sheath　liquid　was　composed　of　isopropanol-water　(1:1　v/v)　containing　30　mM　acetic　acid　with　a　flow　rate　of　4　mu　L/min.　Mass　spectrum　was　employed　in　the　positive　mode　and　both　full　scan　mode　and　SIM　scan　mode　were　utilized.　All　12　diuretics　could　be　detected　and　confirmed　by　MS　in　a　single　analysis.　Under　optimized　conditions,　LODs　for　the　12　diuretics　were　in　the　range　of　0.13-2.7　mu　mol/L　at　an　S/N　of　3,　and　the　correlation　coefficients　R-2　were　between　0.9921　and　0.9978.　The　RDSs　(n　=　5)　of　the　method　was　0.24-0.94　%　for　migration　times　and　1.6-8.8　%　for　peak　areas.　The　recoveries　of　spiked　samples　of　12　diuretics　were　between　72.4%　and　118%.　The　real　urine　samples　were　injected　directly　for　analysis,　with　only　simple　filtration　through　a　0.22　mu　m　membrane　filter　in　order　to　remove　solid　particles,　which　may　cause　capillary　blockage.　Based　on　the　migration　times　and　characteristic　ions,　the　diuretics　in　urine　samples　were　detected　successfully.　This　CE-ESI-MS　method　for　analyzing　diuretics　will　hopefully　be　applied　to　doping　control.