In this paper, a new method for detecting the gravitational waves designed on the basis that the viscosity coefficient of the dark matter fluid may affect the gravitational constant. In this method, the devices that measure the gravitational constant are mainly used to measure the change of the gravitational constant. When gravitational waves pass over, it helps to form an interaction between the sun and the dark matter fluid by means of gravitational waves, thereby transferring part of the sun's heat to the dark matter fluid. Therefore, the increase in this part of the heat will lead to an increase in the temperature of the dark matter fluid. The increase in the temperature of the dark matter fluid leads to an increase in the viscosity coefficient of the dark matter fluid. The increase of the viscosity coefficient of the dark matter fluid directly leads to the increase of the gravitational constant. Since 2015, we have been able to detect the gravitational waves reaching the earth through LIGO and other devices. Therefore, this paper compares the measurement data of the gravitational constant of HUST-18 since 2015 with the gravitational wave data obtained by LIGO. It was found that the measured gravitational constants tend to be higher in the years when gravitational waves were detected. In 2016, when no gravitational waves were detected, the measured gravitational constant was significantly lower.