The thermal state of powder arriving in a molten pool is crucial to the forming precision and quality of the cladding layer for off-axis laser cladding. Aiming at the different melting behavior of powder under the action of light powder, an infrared thermal imaging acquisition system and a high speed camera process acquisition system for the laser cladding process with off-axis powder feeding were built. The light powder thermal interaction under different laser powers and defocus amounts was studied. Three typical characteristic stages of powder melting were established. The influence of laser power and defocus amounts on the duration of the characteristic stage of powder melting was examined. Finally, the relationship between the thermal state of powder and characteristic stage was obtained. The findings depict that with the increase in laser power, the number of melted powder in the interaction space increases and the powder temperature uniformity decreases, and the number of liquid powder particles increases with an increase in defocus and the temperature inhomogeneity of powder decreases. The smaller the laser power or larger the defocusing amount, the time required for the temperature to rise and the solid powder's melting increases. The powder's probability of entering the molten pool in solid state increases. The thermal states of powder arriving at the molten pool under different laser parameters are obtained, providing an experimental basis for the powder melting behavior analysis.