<p>This study analyzed the porosity of the longitudinal section of the iron-based powder cladding layer on the QT500 substrate based on the range analysis method. The results show that the laser power is the main factor affecting the porosity of the iron-based cladding layer. Further analysis of the causes of pore formation reveals that the pore defects in iron-based cladding layers are mainly caused by the carbon gas produced by the reaction between local unmelted powder and metallurgy. As the temperature of the molten pool increases, the reactivity of the gas generation reaction gradually increases. Based on this, by establishing a theoretical model of the influence of the force on the pores on the motion state, the research found that as the temperature of the molten pool increases, the flow velocity of the pores gradually increases, and the flow direction and the escape direction show a change rule of first opposite and then the same. As laser energy density is a key indicator that comprehensively reflects the influence of the main parameters such as laser power, scanning speed, and spot diameter on the cladding process, this study further analyzed the effect of laser energy density on the porosity of iron-based cladding layers. The results showed that with the increase in laser energy density, the porosity first increased and then decreased, with an inflection point of 83.333 (W/mm²).</p>