Abstract: Arc plasma heat flow cutting, as a novel thermal cutting technology, shows excellent application prospects in the field of material processing. To achieve the control of heat and jet during the arc heat flow cutting process, a plasma constricted cutting method was proposed in this paper. To provide theoretical support for the structural design of the constriction tube and achieve the precise control of arc cutting quality, the influence of structural parameters such as tube length, constriction angle, and tube diameter on cutting performance parameters such as jet outlet temperature distribution, jet velocity, jet length, and jet diameter was numerically simulated based on COMSOL software. The variation laws of cutting performance parameters with the structural parameters of the constriction tube were analyzed, and an optimization scheme for constriction tube cutting was proposed based on the calculation results. The results indicate that a shorter constriction tube is suitable for high-precision cutting and the cutting of thicker plates. A smaller constriction angle is suitable for high-quality cutting requirements. A larger tube diameter is suitable for high-precision cutting. Reasonable selection and optimization of the ratio of tube length, constriction angle, and tube diameter can achieve the fine cutting of thick plates.