Abstract: 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.