Abstract: Disclosed is a device and method for generating X-rays having different energy levels as well as a material discrimination system thereof. The method comprises the steps of: generating a first pulse voltage, a second pulse voltage, a third pulse voltage and a fourth pulse voltage, generating a first electron beam having a first beam load and a second electron beam having a second beam load, respectively, based on the first pulse voltage and second pulse voltage, generating a first microwave having a first power and a second microwave having a second power, respectively, based on the third pulse voltage and the fourth pulse voltage, accelerating the first and second electron beams respectively using the first and second microwave to obtain the accelerated first electron beam and the second electron beam, hitting a target with the accelerated first electron beam and the second electron beam to generate a first X-ray and a second X-ray having different energy levels.