Abstract—Amongst the emerging new welding technologies, friction stir welding (FSW), invented and established by The Welding Institute (TWI) in 1991, is used frequently for welding of high strength aluminium alloys such as AA6061, AA6082, AA6351, etc. which are difficult to weld by conventional fusion welding techniques. This paper presents the modelling of FSW for various tool-pin profiles along with simulation of peak temperature induced in plate material and flow stresses generated in the same for friction stir welding of AA6061. The modelling has been carried out by using the FEA software. In present work the three dimensional nonlinear thermal numerical simulations are conducted using Hyper Weld software module for FSW butt joints of AA6061 alloy. Friction stir welding simulation is performed for various tool pin profile at constant 600rpm speed and thermal distribution is analyzed. The results are presented for variations in peak temperatures of aluminium alloy plate as well as flow stresses generated at and around the tool pin during the welding process.