Peat is a type of soil made up of partially decomposed plant matters and contains high amount of pores. Therefore, it has high compressibility and low shear strength, which makes it as a geotechnically problematic soil. Two main methods of ground improvement include mechanical and chemical methods. In this research, chemical stabilization was used as ground improvement techniques and this method stabilizes the soil through the addition of chemical admixtures such as ordinary Portland cement OPC , fly ash, lime etc. Major aim of this research was to study the compressibility characteristics of peat stabilized with ASTM class F fly ash FA using deep mixing method DMM , and an experimental and numerical based study was adapted to achieve the aim. As part of the experimental study, testing including index properties test, direct shear test and consolidation test using Rowe cell apparatus were conducted, while PLAXIS 2D numerical package was used to simulate the laboratory Row Cell consolidation test to predict the consolidation characteristics of peat and FA stabilized peat. A FA dosage of 10 by weight was used to prepare the stabilized peat sample. Based on the experimental findings, peat used was classified as sapric amorphous peat. Addition of 10 FA increases the cohesion c and decreases angle of friction F. Further compressibility parameters coefficient of consolidation Cv, coefficient of secondary compression Ca and compression index Cc decrease with the addition of 10 FA and it is due to the chemical reaction between FA and water in the peat, producing a stiffer peat FA stabilized matrix. Percentage reduction in Cv and Ca are 12.7 33.4 and 7.1 25.93 depending on the normal stress, while the percentage reduction in Cc is 10.5 . In addition, it was observed that PLAXIS can predict the consolidation behaviour of peat reasonably well.