The optimization of a transmission type bremsstrahlung conversion target was carried out with MonteCarlo code FLUKA for intense pulsed electron beams with electron energy of several hundred keV formaximum photon fluence. The photon emission intensity from electrons with energy ranging from300 keV to 1 MeV on tungsten, tantalum and molybdenum targets was calculated with varied targetthicknesses. The research revealed that higher target material element number and electron energy leadsto increased photon fluence. For a certain target material, the target thickness with maximum photonemission fluence exhibits a linear relationship with the electron energy. With certain electron energy andtarget material, the thickness of the target plays a dominant role in increasing the transmission photonintensity, with small target thickness the photon flux is largely restricted by low energy loss of electronsfor photon generation while thick targets may impose extra absorption for the generated photons. Thespatial distribution of bremsstrahlung photon density was analyzed and the optimal target thicknessesfor maximum bremsstrahlung photon fluence were derived versus electron energy on three targetmaterials for a quick determination of optimal target design