A temperature rise model of laser cladding material powder by side-injection is established. In this model, the distribution of laser power is considered. The relation formula between the temperature rise of the powders and the time that the particles moves under the laser beam shine is deduced by considering two kinds of circumstances when the diameter of laser beam is larger or smaller than the diameter of powder spot. The paper presents the relationship between the temperature rise and moving time of the powders for different laser power. The paper also presents the relation between the temperature rise and the interaction time for different powder diameters. The micro-distance photograph technique and the image segmentation technique are used to investigate the state and temperature of the cladding material particles after its passing through the laser beam. The experiment analysis validates the model prediction.