T This study aimed, first investigating the existing condition of a community-based dairy farm with its utilization of biogas reactor seen from such its interrelated components as the breeder, cattle, pasture, water sources, biogas reactors and the non fossil fuels related to the economic gain, community empowerment, and environmental control and second, formulating an optimum model for the community-based dairy cattle enterprise and the biogas utilization in the study area to improve their economic gain, welfare and control the environmental pollution arising from their dairy activities. The study was conducted at Pejaten, upper region of Citarum Watershed, and used a linear programming with TORA software 2nd version 2000, interrelationship variables (breeder, cattle, cattle manure, river, land, biogas). The Net Present Value, Benefit-Cost Ratio and Profitability Index Analysis were used as the economic parameter; while Biological Oxigen Demand and Total Suspended Solid were used for environmental parameter> The result was that the Maximum Profit Formula Y = 155.356 X1 + 238.719 X2 + 790.569 X3 (X1 : calf, X2 L : Dantan, X3 : Adult). The formulion was constructed to maximazi the economic gain of the farm community in the utilization of biogas technology, by considering availability of land for cultivating grass, settlement, cattleshedvand biogas reactor, water resource for community, farming and biogas purposes. A simulation model resulted that the optimum ratio between calf: danten: adult to be cultivated was 1:1:6, than this area study was capable to accommodate 2,155 cattle. With the maximum profit sufiscient to fulfil living cost for the hole family and capable to develop their business. By utilizing reactor Biogas the requirement of cooking energy for the whole community can be fulfil by biogas. Therefore this model was appropriate to apply in the effort to minimize river pollution from cattle manure, and increase the job opportunity. This condition recommend that breeders can work by colloni with minimum of 7 breeders.