Flow-domain extraction in fuel solenoid valve flow-field simulations faces prominent problems. These include repetitive, tedious, labor-intensive processes and low efficiency. A critical limitation also exists with existing methods: full re-modeling of the flow domain is required whenever valve structural parameters are adjusted. To tackle these issues, a tree-structured parametric modeling mechanism was developed on a self-established simulation platform. This mechanism established an explicit mapping between the geometric parameters of the valve and the flow-domain model. Subsequently, an automatic flow-domain extraction algorithm was proposed to dynamically update the flow-domain structure in real time as valve parameters were modified. Experimental results show that the proposed approach enables accurate, automated extraction and rapid updating of the flow-domain model, significantly reducing repetitive manual workload. Compared with conventional methods, the novel procedure exhibits high feasibility and improves the average extraction efficiency by 33.67%.