In this paper, the Bénard-Marangoni convection in the two-layerfluid is investigated experimentally with particle image velocimetry (PIV).Different convection patterns near the critical point are observed.Meanwhile, the transitions from critical convection to supercriticalconvection are studied when the temperature difference $\Delta T$ is rampedslowly. The experimental results indicate that the interface tension playsan important role for the convective patterns near critical point and thetransition of the convection patterns of two-layer fluid.