Abstract In this paper, the fatigue small crack growth rate of selective laser melting (SLM) AlSi10Mg alloy is studied by in-situ SEM experiment. The experimental results show that the small crack growth rate of SLM AlSi10Mg alloy can be described by Paris law, and the crack growth rate increases significantly with the increase in temperature. In addition, the combination of finite element simulation and fracture analysis shows that the pore is one of the main factors affecting the dispersion of small crack growth rate.