In order to improve the water treatment capacity in offshore oilfield, a Dithiocarbamate (DTC) water clarifier product with good performance needs to be developed. This research synthetized three DTC water clarifiers as NQ-101, NQ-102 and NQ-103 by modifying YF-02, T-403 and tetraethylenepentamine(TEPA) with CS2 in laboratory alkaline condition. The research characterized these three DTC water clarifiers with IR spectroscopy, compared their bottle test results with presently used water clarifier Q-30A in the oil field, and carried out on-site pilot test and routine field application for the product having the best performance. The results show that the performance ranking of all 4 water clarifiers is NQ-101＞Q-30A＞NQ-103＞NQ-102. When implementing on-site pilot test and application of NQ-101, the Oil in Water (OIW) discharging from the two Compact Flotation Units(CFU) CFU-A and CFU-B decreased from 20.1 mg/L and 17.5 mg/L to 12.9 mg/L and 11.2 mg/L, clearly showing that NQ-101 has better performance than Q-30A. After increasing field production and moving back injection point of NQ-101, the OIW of overboard discharge is still under 20 mg/L, meeting the requirements of field production. Furthermore, the mechanism of DTC water clarifier actions was proven by detecting every kind of ion. When NQ-101 was routinely applied in the oilfield, the production process is stable and the result is consistently good. This research successfully developed a DTC water clarifier with high performance through synthetizing and field application, which improved oily wastewater treatment capacity in offshore oilfield.