With an intention to potent inhibitors of YycG histidine kinase, a series of halogenated thiazolo[3,2-a]pyrimidin-3-one carboxylic acid derivatives were synthesized and evaluated for their antibacterial, antibiofilm and hemolytic activities. The majority of the compounds showed good activity against Staphylococcus epidermidis and Staphylococcus aureus, with MIC values of 1.56-6.25 μM, simultaneously presented promising antiobifilm activity against S. epidermidis ATCC35984 at 50 μM. The test of inhibitory activity on YycG kinase suggested the antibacterial activities of these derivatives are based on inhibiting the enzyme activity of the YycG HK domain. The hemolytic activity test suggested these compounds exhibited in vitro antibacterial activity at non-hemolytic concentrations.