The action and distribution of laser heat in the powder and melt pool during coaxial powder feeding laser cladding has an important influence on the forming quality. This paper conducted research on the complex and challenging thermal interaction between powder and laser， particularly difficult to detect in real-time infrared analysis. Firstly， a high-speed camera system is established and the melting process of a single powder coaxially fed into the laser was collected and analyzed， and the thermophysical behavior of different characteristic stages of the powder melting process is studied and a mathematical model is established. Moreover， due to the difficulty in validating and optimizing the model based on valid temperature data， the duration of the different characteristic phases was statistically analyzed using high-speed cameras， and was compared with the calculated results of the model. Finally， based on the optimization of the model， the simulation predicted the temperature and state of the powder about to enter the melt pool， which provides a theoretical basis for further analysis of the thermal interaction between the powder and the melt pool. The results show that： there is a transition of “solid → solid-liquid two-phase state → liquid” after a single powder enters the melt pool， and the duration and thermophysical behavior of different transition processes are not the same； the mathematical model established by this can dynamically describe the duration and temperature characteristics of different melting stages after the powder is fed into the laser. The validity and accuracy of the model were verified by comparing with high-speed camera statistics. The simulation predicted the temperature characteristics of the powder when it was about to enter the melt pool， and analyzed the influence and effect of different laser powers on the state of the powder when it is about to enter the molten pool.