The powder stream has an important influence on the quality of coating in coaxial laser cladding. In order to improve the convergence of powder stream, a numerical model of powder stream in coaxial laser cladding is developed based on a given coaxial nozzle. Simulations of three kinds of powder stream, including NiCoCrAlY, ZrO2 ceramic powder and W powder, are calculated and validated by the experimental results. The effect of powder properties, including particle diameter, shape, density and restitution coefficient, on the convergence of powder stream is investigated. According to the calculated results with the same powder feeding parameters, as the particle diameter increases, the powder flow focal distance decreases, and the powder concentration reaches a maximum within some particle diameter scale. The powder concentration gets bigger and the powder flow focal distance becomes shorter with the powder shape factor or powder density increasing. As restitution coefficient decreases, both powder flow distance and powder concentration increase.