In this work, based on a finite difference scheme, we propose the weak Galerkin (WG) method for solving time-fractional biharmonic equations. Theoretically and numerically, the optimal error estimates for semi-discrete and fully discrete schemes have been investigated. Based on mathematical induction, stability is discussed for the fully discrete scheme that depends on the initial value and the source term. Numerical experiments are provided to confirm the theoretical claims made by the proposed schemes.