To date, the simulation of hydrogen-blended natural gas has been unable to effectively balance the two parameters of calculation accuracy and simulation speed, which is not conducive to guiding the rapid decision-making of on-site operation plans. To address this issue, decoupling simulations were conducted on the component tracking equation, hydraulic equation and thermal equation. The differences between the coupling model and the TGNET model, as well as between the coupling model and the decoupling model, were analyzed. The optimal time step and spatial step were determined. Single instruction multiple data (SIMD) parallel computing technology was introduced. The rapid processing of the intermediate parameter-solving process was then implemented using the AVX2 instruction set, and the calculation and analysis were carried out with actual cases. The results of the coupling model are in high agreement with those of the TGNET software. The computing times of the two models are 8237 ms and 8359 ms, respectively, and they show consistency and compatibility. When calculating the decoupling model, it is more appropriate to use a time step of 90 seconds and a spatial step of 1 km. Compared with the coupling model, the speedup ratio with this combination is 2.89. Compared with the maximum pressure-maximum flow boundary condition, the errors in pressure, temperature and hydrogen molar fraction under the maximum flowmaximum flow boundary condition all increase. It is recommended to give priority to using this boundary condition in applications such as pipeline network planning and design, operation peak shaving, sudden gas consumption and gas supply safety redundancy guarantee. Compared with the decoupling model, the computational speedup ratio after introducing SIMD instructions is 2.68, which is lower than the upper limit of the theoretical speedup ratio. These results can provide a theoretical basis and practical reference for the simulation of large-scale hydrogen-blended natural gas pipeline networks.