X-ray radiation using pyroelectric crystal is intermittent and the X-ray intensity is low and unstable compared with a conventional X-ray radiation method, such as X-ray tube. It is expected that the X-ray intensity becomes stable if electric field intensity and supply of electron are stable. In this study, to use X-ray radiation equipment as an electron source, tandem-type X-ray radiation equipment which is composed of two LiNbO3 single crystals polarized in a z-axis is proposed. When the temperature gradient for each crystal was the same, the X-ray intensity became approximately 6 times higher at a maximum. When the temperature gradient for each crystal was reversed, the period of X-ray radiation became approximately two times longer and the X-ray intensity became approximately 20 times higher at a maximum. Moreover, the stability of X-ray radiation for the repetition of temperature could be improved.