In　this　work,　core　CdTe,　core-shell　CdTe/CdSe　and　alloy　CdTeSe　QDs　are　synthesized　by　aqueous　solvent.　TEM　visually　shows　the　rod-shaped　core-shell　structure　with　a　transverse　to　longitudinal　ratio　of　6.5　and　the　ellipsoidal　alloy　structure　with　different　crystal　planes　competing　for　growth.　The　XRD　and　Raman　spectra　of　the　three　QDs　illustrate　the　characteristics　of　the　internal　lattice　structure.　With　the　increase　of　reaction　time,　CdTe　emission　maximum　(EM)　shows　a　red　shift　of　84　nm.　Stokes　shift　changes　little,　and　full　width　half　maximum　(FWHM)　increases　slightly.　Compared　with　the　CdTe,　the　red　shift　of　CdTe/CdSe　EM　is　slowly　first　and　then　faster,　with　a　total　shift　of　125　nm.　Stokes　shift　increases　obviously.　The　initial　FWHM　is　larger　than　CdTe　and　the　widening　speed　is　gradually　accelerated.　The　initial　EM　of　CdTeSe　is　red　shifted　compared　with　CdTe,　and　the　total　red　shift　of　EM　is　72　nm.　Stokes　shift　increases　obviously.　The　initial　FWHM　is　significantly　wider　than　CdTe.　FWHM　first　decreases　and　then　increases　with　reaction　time.　CdTe　shows　obvious　band　edge　exciton　absorbance　of　photoluminescence　excitation　(PLE)　spectrum　between　356　nm　and　400　nm.　CdTe/CdSe　shows　double　band　edge　exciton　absorption　at　354-373　nm　and　401-436　nm　due　to　wave　function　separated　of　core-shell　structure.　The　PLE　spectrum　of　CdTeSe　shows　an　obvious　upward　trend　at　306-373　nm　due　to　high　energy　level　nonradiation.　The　average　lifetime　of　CdTe/CdSe　increases　by　53　ns　compared　with　CdTe　due　to　the　spatially　separated　electrons　and　holes.　The　defect　state　of　CdTeSe　increases　the　proportion　of　fast　delay,　which　is　2　ns　shorter　than　the　average　lifetime　of　CdTe.　The　transition　mechanism　of　core-shell　indirect　band　gap　and　alloy　direct　band　gap　is　explained　according　to　the　valence　bands　of　each　element　shown　by　XPS　and　the　simulation　of　energy　band　density　of　states.　The　thickness　shell　and　the　doping　elements　can　be　adjusted　to　provide　rich　variation　in　the　optical　properties.　This　provides　a　more　definite　direction　for　the　applications　of　cadmium　chalcogenide　in　the　fields　of　photoelectric　devices　and　biology.　(C)　2022　Elsevier　B.V.　All　rights　reserved.