In this seminar, we prove the stability of Couette flow for the 2D Navier-Stokes Boussinesq system without thermal diffusivity for the initial perturbation in some Gevrey spaces. The synergism of density mixing, vorticity mixing, and velocity diffusion leads to the stability. The result is proved by applying the energy method together with a bootstrap argument to a carefully designed energy norm. This result extends some previous works.