Physically peat is known as the soil with organic matter and water content is very high, the number of large pores, heavy volume of small dirt and shear strength is low, while technically very important to the peat soil is compression is high, and the ability to support low loads. Civil engineering building damage caused not only by the structure of the building, but also the condition of the soil on which the building structure is laid. The cause of the malfunction is the magnitude of the downturn and low carrying capacity of the land, for it must be considered carefully whether the need for improvement or stabilization of the soil to get the soil properties are desirable so that the damage can be prevented construction. Various methods of soil improvement has been developed, one of them with soil stabilization as alternative problem-solving to the decline and low ground bearing capacity. One of the alternatives given in this modeling that rice husk ash (RHA) as a filler material for stabilization of shallow foundation on peat soil. This research aims to determine the carrying capacity of the soil and settlement that occurred on variation RHA mix modeling using the assistance Plaxis program version 8.2.  The result showed Central Kalimantan peat soil type has high organic content of 80.15%. High levels of organic matter in peat impact on heavy volume or bulk density of peat soil are low, amounting to 1.06 gr / cm3 making the the peat soil that is too loose with the value of void ratio of 6.0398. Triaxial testing results with the original conditions of UU on the ground that the value cohesi (c) of 0,645 kg / cm2 and f value of 8.6 °, while the addition of RHA content of 8%, during the 3-day ripened c value of 0.3089 kg / cm2 and a value f of 29.53 °. RHA mixture can increase soil bearing capacity greater than 100% of the proceeds qu native soil. Results qu in the peat soil without mixing of 750.612 kN / m2, while the addition of a mixture of variety RHA's largest qu values obtained at the rate of 11% ripened seven-day period in the amount of 2162.763 kN / m2 and the smallest qu value at a level of 5% ripened one-day period with a value of 1010.885 kN / m2. 
Keywords : Rice Husk ASh, Peat Soil, Bearing Capacity, Settlement, and Plaxis.