A new uranyl Schiff base complex, [UO2 (L) (DMF)] where L=2, 2' - ((1E, 1E') - (1, 2 phenylen bis (azanylylidene)) bis (methanylylidene)) bis (4-bromo phenol) by reaction between of H2L and (CH3COO) 2UO2·2H2O was successfully synthesized. The complex characterized by FT-IR, 1H NMR as well as electronic and luminescence property measurements. This complex was used as a novel precursor for preparing U3O8 nano powder at low temperature (400oC) by decomposition method. The average crystallite size of the U3O8 nano powder that has been synthesized is about 22. nm as determined by the Scherrer equation. According the results, we found that U3O8 could stop biofilm formation in S. aureus PTCC 1112 (0.632 mg/ml), M. luteus PTCC 1110 (0.633 mg/ml) and E. faecalis (0.633 mg/ml). Also, U3O8 repressed biofilm formation in M. luteus PTCC 1110 (0.625 mg/ml), E. faecalis (0.313 mg/ml) and C. albicans PTCC 5027 bacterias (1.27 mg/ml).