Thermalsolutal convection induced by mass and heat source in horizontal cavity is investigated numerically based on SIMPLE algorithm with QUICK scheme. The high-concentration heat source is placed in the square cavity, and the cavity wall is low temperature and low concentration. The smoke is used as the diffusion medium, and the flow field, temperature and concentration of the fluid under different Rayleigh number, buoyancy ratio Nc, Soret numbers and Dufour numbers are analyzed. Parameter study demonstrates that heat and mass transfer of thermosolutal convection are enhanced with increasing Rayleigh number or buoyancy ratio, and the couple-diffusive interaction has a significant linear effect on heat transfer and mass diffusion. The results also show that double-diffusive develops from steady state, periodic oscillatory, double-period oscillation to chaotic state. Critical Rayleigh number of period oscillations and chaos declined with buoyance increases.