Abstract: The formation of phosphorus nuclei through proton capture by silicon isotopes is a critical process in the hydrogen burning stage of nova explosions. However, experimental measurements of the associated nuclear reactions face significant challenges due to the involvement of short-lived nuclei. Calculating the spectroscopic factors for these nuclear reactions can provide a theoretical basis for estimating the reaction cross sections, offering valuable guidance for experimental studies. This work focuses on the direct proton capture processes leading to phosphorus nuclei along the silicon isotopic chain. Based on the nuclear shell model, we calculate the relevant spectroscopic factors. The results obtained for proton capture on ^25-28Si are in good agreement with existing experimental data and theoretical calculations. Furthermore, we predict for the first time that the proton spectroscopic factor for the ground state of ²⁵P is approximately 0.6.