Based on spatial-temporal symmetry breaking mechanism, we propose a novel scheme for terahertz (THz) wave generation from hyper-Raman lines associated with the 0th harmonic (a particular even harmonic) in a two-level quantum system driven by two-color laser fields. With the help of analysis of quasi-energy, the frequency of THz wave can be tuned by changing the field amplitude of the driving laser. By optimizing the parameters of the laser fields, we are able to obtain arbitrary frequency radiation in the THz regime with appreciable strength (as strong as the typical harmonics). Our proposal can be realized in experiment in view of the recent experimental progress of even-harmonics generation by two-color laser fields.PACS numbers: 42.65. Ky, 42.50.Hz, 78.20.Bh Introduction Terahertz (THz) radiation, electromagnetic radiation with typical frequency from 0.1 THz to 10 THz-lying in the spectrum gap between the infrared and microwaves, has varieties of applications in information and communication technology, biology and medical sciences, homeland security, and global environmental monitoring etc.1 . The generation of THz wave is a challenge problem due to the lack of appropriate materials with small bandgaps in the usual optical approach. Great effort has been made to the design of THz sources 2-15 . THz wave can be obtained by both electronic and optical methods. The uni-travelling-carrier photodiode 6 and the quantum cascade laser 9-13 are two examples. The electronic approach is limited in the low frequency end of the THz regime, and the optical approach usually focuses on the cases of small energy gap. Technological innovation in photonics and nanotechnology has provided us more new ways for THz radiation generation. Recently an interesting approach based on semiconductor nanostructure driven by acoustic wave was suggested 16 , and electrically pumped photonic-crystal THz laser was developed 17 . THz wave generation by up conversion method through high-order harmonics generation(HHG) in semiconductor quantum dot(QD) was also suggested in our previous work 18 .