In this paper, a four-molecule reversible biochemical reaction-diffusion model combining second-order saturation subject to homogeneous Neumann boundary conditions is studied. Taking the reversible reaction rate as a parameter, the existence, direction and stability of Hopf bifurcation for ordinary differential system and the diffusive system are respectively given applying the normal form theory and the central manifold theorem. Moreover, the effect of diffusive coefficient on the stability of the system is studied extensively. The results show that the positive equilibrium point is unstable when the reversible reaction rate is small. When the reversible reaction rate is large, the positive equilibrium point is stable. When the reversible reaction rate is in a certain range, the diffusive coefficient has a great effect on the stability of the system. In this case, if the catalyst's diffusive coefficient is small, then Turing instability occurs. Finally, the parameters satisfying the conditions of the theorem are selected and the theoretical results are verified by numerical simulations.