A device and method of enhancing terahertz wave signals based on a hollow metal waveguide are disclosed. Simple devices such as a beam splitter, multiple plane mirrors, a beam combiner and an adjustable delay system are used. Two laser beams having a wavelength of 800 nm split by the beam splitter generate a fixed time phase delay, and are converged in the hollow metal waveguide to sequentially overlap with pulse of a laser having a wavelength of 400 nm for nonlinear interaction to ionize gas in the optical fiber to generate terahertz waves. The hollow metal waveguide can converge and transmit the generated terahertz waves due to its total reflection characteristics.