Room temperature phosphorescent (RTP) carbon dots (CDs) have the disadvantages of short lifetime, single wavelength and poor stability. Phosphorescence usually suffers severe thermal decay due to strong non-radiative transitions caused by temperature increasing, limiting the use of CDs. Herein, α-Cyclodextrin provides hydrophobic cavities, so for CDs can be encapsulated into this cavity. OH on cyclodextrin also reacts to generate covalent bonds. Both of them restricts the rotation and vibration of the benzene ring and reduces the non-radiative transitions. Compared to the matrix-limited domain, the cavity encapsulation has a better wrapping effect, while the hydrophobic cavity can better isolate the O