The novel nanozyme has been used in the detection field as biosensor, but has also been employed in newfields like antibacterial and inhibiting of biofilm growth applications. This paper reports the rapid preparationof the nanozyme PS-CDs-MnO2 with oxidase activity by using PS-CDs as reducing agent to reduceKMnO4. The mechanisms of positive electrical property of PS-CDs-MnO2 and the single linear oxygen(1O2) have promised the broad-spectrum antibacterial ability and high efficiency in eliminating bacteria,with 48 h long-term antibacterial effect. The minimum inhibitory concentration (MIC) againstStaphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Pseudomonasaeruginosa (P. aeruginosa) at 7.50 lg/mL, 60 lg/mL, 15 lg/mL and 60 lg/mL, respectively. The preparedPS-CDs-MnO2 could effectively inhibit the formation of S. aureus biofilm at the concentration of 10 lg/mL. The visually sensitive and selective sensing platform based on PS-CDs-MnO2-TMB was established, andrealized the colorimetric detection of tiopronin (TPN) with a detection range at 285.71 nM–14.28 lMand detection limit at 6.30 nM. This research provides a good theoretical and practical basis for the preparationof oxidase nanozyme and its application in detection, antibacterial and inhibition of biofilm formationfields.