This waste water treatment plant (WWTP) was designed and built to treat the waste water coming from the sting rays leather tannery in Labuan Maringgai, Lampung Selatan. By treating this kind of waste water coming from the sting rays leather tannery, it will decrease the environmental pollution. The product capacity of this tannery was 400 pieces per month and the weight of it was 120 kg. Those skins were tanned into two steps, the number of skins in each process was 200 pieces or 60 kg during 2 weeks. The volume of waste water discharged varied from 1,5 to 5 m3 during 3 days in the beginning of beam house operation or 0.5 to 1 m3per day during the first step of process. The pollution content of such waste water was as follows: COD: 1205,66 - 1400 mg/l; BOD 550 – 950 mg/l; S : 28,9 – 213 mg/l, TSS: 55,16 – 775 mg/l; N-NH3 : 30,18 – 129,6 mg/l; fat/oil : 21 – 292. mg/l; total Cr: 0,47 – 0,76 mg/l; and pH: 9 – 12 respectively. The work hours in operating the WWTP was 5 hours per day, and the debit of it ranged from 0.5 to 1 m3 per hour. The WWTP was designed for the max COD of 1.500 mg/l and BOD 750 mg/l. The system of WWTP was pre treatment, homogenization, flocculation and coagulation, 1st anaerobic facultative and 2nd anaerobic facultative, sludge drying bed and final control tank. The efficiency of this WWTP ranged from 22,53 to 97%.