Laser　self-mixing　interferometry　(SMI)　is　often　used　for　displacement,　vibration,　and　velocity　measurement.　At　present,　the　measurement　accuracy　has　reached　tens　of　nanometers,　but　it　has　not　been　used　for　single　cell　detection.　In　this　research,　a　microfluidic　chip-based　equipment　using　SMI　technology　for　label-free　single　cell　detection　was　demonstrated.　The　detection　experiments　were　performed　to　verify　chicken　erythrocytes　and　human　breast　cancer　cells　T47D.　In　order　to　better　analyze　these　data,　the　Hilbert　transform　was　used　to　convert　the　time　domain　signal　into　phase　information.　It　is　found　that　there　are　more　fringes　in　the　signal　of　larger　breast　cancer　cells.　The　power　spectrum　of　the　signal　shows　that　the　velocity　of　the　cell　is　positively　correlated　with　the　Doppler　shift.　The　new　method　for　single　cell　detection　proposed　in　this　paper　provides　a　new　idea　for　real-time　cell　detection.