I will be talking about joint work with Yott. Extending the work of Kudla–Millson and Yuan–Zhang–Zhang, we construct special divisors on a specific GSpin Shimura variety. We further construct a generating series that has as coefficients the cohomology classes corresponding to the special divisor classes $Z(x, g)_K$ on the GSpin Shimura variety $M_K$ and show the modularity of the generating series in the cohomology group over $\textbf{C}$.