The invention provides a dielectric-metal photonic crystal, a preparation method thereof and a tera-hertz pulse generator. The dielectric-metal photonic crystal has a multilayer composite structure represented in the following formula: [dielectric layer/metal layer]n/insulating substrate, wherein n is an integer in 1-10. The metal layer has a multilayer structure which is formed through alternatively combination of magnetic nanometer films and non-magnetic nanometer films. Compared with the prior art, the dielectric-metal photonic crystal according to the invention is advantages in that a specific structure is utilized, laser energy can be absorbed to a greater extent for exciting each metal layer to generate the tera-hertz pulse on one hand, and on the other hand, the tera-hertz pulses which are generated by the metal layers can be overlapped in a coherent manner, thereby greatly improving tera-hertz strength. The dielectric-metal photonic crystal applied to the tera-hertz pulse generator can maximally utilize femto second laser energy, thereby greatly improving tera-hertz strength and realizing wide frequency spectrum and adjustable polarization.