Abstract: Selective laser melting（SLM） molding has important value in additive manufacturing. The influence of different technological parameters on the thermal process of SLM is still to be further studied. The study in a combination of a series of complicated physical and chemical phenomena in the process of forming, on the basis of establishing the SLM forming temperature field numerical simulation model of 316L stainless steel, laser power, scanning speed and scanning interval of SLM and molten pool size, the influence of the temperature field and the reliability of the results of numerical simulation was verified by experiment. The results show that the effect of laser power and scanning distance on the temperature field and the weld pool size is great, but the effect of scanning speed is relatively small. When the laser power is small, the scanning rate is large or the scanning spacing is large, the temperature in the temperature field decreases, the size of the molten pool is small, and hole defects are easy to form. Under the above conditions, the spheroidized powder particles and holes appear on the surface of the model surface, the stability of the molten pool decreases, and the forming quality decreases.On the contrary, the molten pool is relatively stable, and the surface quality greatly improves, but a small amount of spatter occurs. The experimental results are basically consistent with the numerical simulation results, which ensures the accuracy of the numerical simulation results.