The research presented in this paper focuses on the laser-powder interaction. Through the experiment with metal powder in micrometers, we found that, in an invariable laser power density, the thickness of the final fabricated thin wall was similar to the geometrical dimension of the powder line, but could be much greater than the laser focus spot, even greater than two orders of magnitude. Furthermore, this paper showed that, the unmelted and semi-fused particles were concentrated. Thus, in this paper, combining the optical scattering theory with capillarity and infiltration theory pointed out the inducement effect of laser and the self-melting of powder. Based on the experimental phenomena and theory, we get our own ideas on the laser micro-fabrication.