Abstract: Aiming at the variable-diameter and variable-pitch spiral shaft structure in the biomass fuel compression and conveying equipment, a parametric calculation model was established through the analysis of its compression and conveying mechanism. A 14 inches spiral shaft was taken as an example to design the structure, and the compression and conveying process of corn stalk was numerically simulated. Finally, the compression and conveying performance of the spiral shaft was further verified by prototype test. In numerical simulation, the compression ratio of corn stalk reaches 2.408. The experimental results of corn stalk compression and conveying show that the compression and conveying effect of the variable-diameter and variable-pitch spiral shaft structure designed by the parametric calculation model is good, which is in line with the expected standard of corn stalk compression and conveying. The design method using parametric calculation model has certain feasibility and can be extended.