Diurnal dynamics of DOC and POC in two shrimp ponds were studied. It was shown that: DOC concentration decreased from 14: 00 to 18: 00, increased from 18: 00 to 22: 00, then decreased again, and ranged from 3. 22 mgPL ( Pond 1) to 1. 24 mgPL ( Pond 2) ; while POC concentration increased gradually in daytime( 6: 00- 18: 00) and decreased gradually at night( 18: 00- next 6: 00) , and ranged from 1. 28 mgPL( Pond 1) to 1. 26 mgPL( Pond 2) . The pond with a high POC concentration was also with a high DOC concentration. The rates of DOCPPOC decreased gradually in daytime( 6: 00- 18: 00) , increased gradually at night( 18: 00- next 6: 00) , and peaked at 2: 00( Pond 1) and 6: 00( Pond 2) . The diurnal ratios of DOCPPOC averaged 1. 6P1. 0( Pond 1) and 1. 9P1. 0( Pond 2) . CPN ratios of suspending organic particulated matters were the biggest at 18: 00 and decreased gradually at night( 18: 00- next 6: 00) .