In this study; the effect of the electron density over the Br atoms raising with increasing number of CH2 group using the results of the K X-ray cross-sections and average fluorescence yields of bromine in quaternary-imidazole ring. In the experimental set-up, 50 mCi 241Am source and a collimated Ultra-LEGe detector were used. The electron density on the Br atoms raises according to the number of the CH2 groups on the contrary of the inductive effect. The decreasing of the X-ray fluorescence parameters is interested with the increasing the electron density of Br atoms.