The invention provides a preparation method of carbon quantum dots for temperature sensing, and a product thereof. The preparation method comprises: forming a solution I from a carbon source aqueous solution and a phosphorus-containing passivation agent, carrying out microwave treatment for 1 min-5 h by controlling the microwave intensity at 20-400 Hz, carrying out centrifugation to obtain the aqueous solution of particles with a particle size of less than 10 nm, and carrying out rotary evaporation to remove the aqueous solvent so as to obtain the temperature-sensitive product carbon quantum dots having fluorescent property. The present invention further provides the product of the preparation method. According to the present invention, the preparation process is simple, the time consumption is short, and the product is the carbon quantum dots for temperature sensing.