Abstract: A novel diode was designed to produce large-area X-ray and the electrons utilized were mainly from the upstream conical Magnetically Insulated Transmission Line (MITL). The diode is characterized by the use of large angle incident electrons to produce bremsstrahlung radiation. The diode was simulated and analyzed by a combination of two-dimensional Particle-In-Cell (PIC) and MCNP 4C software, and a uniform X-ray area could be found at the downstream of the diode. This paper presents a new idea on how to set the MCNP source better to reflect the angular uniformity. The relationship between three important parameters of the diode and the electrons transportation character are studied. The results show a uniform X-ray field could be obtained using this diode without additional electron transport control structure.