Abstract: Abstract: A molding machine of substrate grass seed blanket can take agricultural waste straw and livestock manure as the raw material, in order to fabricate the grass seed blanket after hand-holding and molding, particularly for the green lawn. Among them, aerobic fermentation can be also adopted to add the premixing liquid for complete decomposition. The continuous uninterrupted molding can be realized after drying below 60℃, transportation, and laying. The substrate grass seed blanket can be laid directly or half-buried in the ground for the urban, park, and residential greening. However, the existing molding machine cannot fully meet the large-scale production in the design of the initial size parameters. The weight of the larger support burden can tend to cause the uneven force of substrate at the extrusion outlet during extrusion molding. This study aims to reduce the component force deformation for better molding stability. Structural optimization was implemented with the extrusion outlet at the neck length, neck width, material plate thickness, and bolt hole diameter as the object using ANSYS Workbench 19.2. The maximum deformation was 0.85 mm, and the maximum equivalent force was 191.25 MPa, using parametric modeling. The response surface method (RSM) with multi-objective optimization was used to optimize the design of the squeeze outlet model. The maximum deformation was 0.54 mm, and the maximum equivalent force was 164.85 MPa. The topological optimization of the extrusion port was carried out to remove the unnecessary material dimensions without affecting the static analysis. The total weight of the part was reduced by 36.60%. EDEM software was used to verify the optimized extruded parts as a whole machine. The grass seed blanket molding was analyzed by the discrete element method with a simulation time of 30 s. Furthermore, the data extraction of the test indicators was performed by the post-processing module. The simulation was performed with the molding particle density and extruded particle quality as the indicators, which were 1 383.2 kg·m-3 and 2 685 g, respectively. The test prototype was made to conduct the germination and drying validation tests. The measured density and mass of the formed substrate grass seed blanket were obtained with an error of 6.7% and 2.7%, respectively, compared with the simulation. The validation test was compared with the test before optimization. The density of the formed particles and the mass of the extruded particles were significantly improved by 5.84% and 2.88%, respectively, before optimization. Consequently, the optimized extrusion outlet can be expected to improve the working efficiency of the forming machine. The formed grass blanket was enhanced with the increase of density between the particles of the substrate grass seed blanket. The quality of the blanket can also fully meet the requirements of the production use in the forming machine of substrate grass seed blanket.