Sliding ferroelectric materials that introduce electric dipole moment through interfacial interactions have been attracting great attention during recent years, owing to their easy fabrication and large contrast signals. Collaborated with Prof. Chunmei Zhang and Prof. Ping Guo at Northwest University in China, we introduce spin polarization as an additional degree of freedom into sliding ferroelectric materials, which provides a large space for its symmetry control. The symmetry arguments for each state has been enumerated, which determines the bulk photovoltaic effect generation. Using various material platforms, we demonstrate such selection rules via first-principles calculations. Our paper has just appeared in Nano Letters, at https://pubs.acs.org/doi/10.1021/acs.nanolett.2c02802.