A non-linear converging die profile for extrusion of square section from round billet was designed using cosine function. MATLAB 7.1 was used to find out the co-ordinates of the cosine die profile. A solid model was generated using AutoCAD 2008 from the above generated points. The STL files of extrusion die generated in AutoCAD was used in DEFORM-3D for FEM simulation. Experimental investigation of extrusion of square section from round billet using non-linear converging dies were done for different percentage of reduction of cross section in dry and lubricated condition. All the experiments were done using FIE‟ Electronic Universal Testing machine (UTM), model UTS-100 with maximum capacity of 1000 kN with accuracy ±1.0% kN. Material properties of lead like flow stress and frict ion factor were determined using compression and ring compression tests under different boundary conditions.To study the flow pattern of the material during extrusion, experiments were done with split work piece in lubricated condition by making grid. The extrusion load with punch travel was compared with extrusion load with solid work piece under same experimental condition. It was found that extrusion load in splitted work piece is less than the work piece when solid. FEM simulation of extrusion of square section from round billet for pure Lead and aluminium-1100 as work material were done using DEFORM-3D 6.1 (sp1). For FEM simulation the linear converging and cosine (non-linear converging) die profiles are used. FEM simulation using leads were done for two frictional conditions 0.38 and 0.75 corresponding to dry and lubricated conditions. Extrusion was assumed to be isothermal. From present investigation it was found that the extrusion load in case of cosine (non-linear converging) die is less than the linear onverging dies under same condition. The extrusion load increases with increase in reduction and friction factor.