In order to research the erosion effect of underground hot water on limestone,the paper applied water chemical simulation software ‘phreeqc’ of the federal geological survey to carry out water chemical simulation to the dissolved rate of calcite in different breach pressure of CO2points ,temperature and period of solution. The simulation results show that under the open state, CO2pressure points is 10-4.5 MPa, the dissolved rate decreases with the passage of time; the rate increases with the rise of temperature. The greater the pressure of CO2points of underground hot water, the higher the temperature, the more the erosion ability of limestone.