The visual and real-time monitoring of temperature has always been an attractive research direction. Fluorescent sensing is a semi-invasive temperature detecting method with the advantages of high-sensitivity, rapid-response and real-time visualization, which has been widely applied in biomedicine. However, conventional fluorescent detecting results can be easily effected by the fluctuation of external conditions which can cause deviation. Therefore, ratiometric fluorescent probes have been developed to solve this problem, because the two fluorescent signals can achieve intercalibration, improving the accuracy of the method. Traditional ratiometric fluorescent temperature probes are always based on down-conversion emission (fluorescence). This type of probes requires excitation at short wavelength like ultraviolet, which has poor penetrability and potential damage to biological tissues. Besides, the auto fluorescence from tissues become strong interference to the probes. Frequency upconversion is a photoluminescence phenomenon excited at long wavelength and emitting at short wavelength. Fluorescent probes based on upconversion can overcome the drawbacks of conventional ones. Triplet-triplet annihilation (TTA) upconversion system requires two kinds of molecules, sensitizer and emitter, and has both up/down-conversion itself, which perfectly meets the requirement of ratiomatric fluorescent probes. However, ratiomatric fluorescent temperature probes based on TTA upconversion are barely reported, and even in the reported work, additional reference probe is still needed. Ratiomatric fluorescent temperature probes only based on the up/down-conversion luminescence of TTA system itself is still a great challenge. Herein, a traditional TTA system (PdOEP/DPA) is encapsulated into micelles assembled by amphipathic polymer, Pluronic-F127, yielding a TTA upconversion nanoscale micelle temperature probe. As the temperature rises, the hydrophilicity of PEO segment in Pluronic-F127 decreased, yielding the micelles shrink inward and become smaller. The confined space inside the micelles results in greater collision probability of the TTA molecules, causing higher TTA upconversion efficiency and intensity. Meanwhile, the phosphorescence intensity of sensitizer slightly declines. The ratiometric fluorescence composed of up/down-conversion fluorescence signals of the TTA system can achieve linear detection of temperature from 25 to 60 ℃, which can be observed by naked eye due to the color change of the emitting light from magenta to violet. The detecting results also have good repeatability. Encapsulated by thermo-sensitive polymer, the TTA system can be applied both in aqueous solution and in air atmosphere, solving the problems of poor water solubility and quenching by oxygen. Besides, the thermos-sensitive polymer brings the TTA system remarkable temperature response capability. This novel type of ratiometric fluorescent probe based on TTA upconversion micelles shows advantages of simple preparation, great biocompatibility, high sensitivity and human eye recognition. No extra reference probe is needed. This method will open an efficient avenue for vivo temperature detection.