The  objective  of  this  study  was to  evaluate  the  effect of  rice bran as  carbohydrate  source  and  inoculums of lactic acid  bacteria  (LAB) incubated from  PO  catles rumen fluid  on the quality  of  napier   grass  (Pennisetum  purpureum ) silages.  The  research  was  conducted  at Ujung ujung  village Pabelan  District  Semarang  Regency.  Feed  analysis  was carried out   in Laboratory   Biochemical   Nutrition, Animals Feed   Science, Animal   Science   Faculty, Gadjah   Mada University. This study  was  assigned  into  Completely  Randomized  Design  wth  4 treatment s  and 3 replicated. The treatments  were : T0 =  0% 0f  rice bran  ; T1 = 1%  of rice bran and inoculums of lactic  acid 0,1% v/w; T2 = 3% rice brand and inoculums of lactic 0,1% v/w; T3 = 5% rice bran and inoculums of lactic acid  0,1 v/w  and incubated  for  30 days . The results  showed that  the  addition  of 1–5% rice bran  significantly  affected (P<0,05) lactic acid content , pH,  dry matter and organic matter   content than without treatment    increased levels, adecrease in pH   and content of dry   matter and organic matter from Napier   grass silage. Increasing   level of   rice bran   significantly   (P<0,05) increased   lactic   acid content, decreased, pH   dry matter, and organic matter   concentration   of Napier grass silage.   However , among the treatment  groups  of  1,  3, and 5% of rice bran  was not significant  (P<0,05) different on  the lactic acid  content,  pH, dry matter and organic matter