To figure out the relationship between ultra-high pressure homogenization (UHPH) treatment and survival of microorganisms, watermelon juice was homogenized under pressures ranging from 0 to 150 MPa and its microbiological indexes were examined. After homogenization at 150 MPa , the total bacterial count (TBC) of watermelon juice decreased by 2.0 to 2.3 logarithm unites, and the total yeast and mold count decreased by 3.1 to 3.5 logarithm unites, but the Bacillaceae count changed little. After once homogeniz...