The development of high-power, high-energy, high-efficiency terahertz radiation sources that can operate stably at room temperature is a practical problem that urgently needs to be solved in the field of terahertz technology. Based on the transient photocurrent model, this paper studied the physical process of three-color laser pulse-induced terahertz waves in liquid media by numerical simulations, and analyzed the effects of phase difference, intensity ratio, wavelength, and pulse width on the terahertz radiation. The simulation results show that the phase differences, the intensity ratios, the wavelength and the pulse width have obvious effects on the terahertz electric field. At the same time, only the tunnel ionization mechanism in which the ionization rate changes with the oscillation of the laser electric field can generate transient photocurrents, thereby obtaining terahertz radiation.