X-ray radiation with an average flux of 1.3×107 photons·sr-1·s-1 is generated by the interaction between ultra-short laser and solid target working at 1 kHz repetition rate. A knife edge is introduced to measure the source size. The X-ray emission shows obvious dependences on the laser contrast and intensity. It is discovered that at lower intensity the Kα yield increases with lower laser contrast. However, by using high contrast and high intensity laser pulses, high flux and high signal-to-noise ratio Kα X-ray can be generated. The generated source is used in proof-of-principle radiograghic imaging of simple specimens.