This thesis work is identified effects of geometrical parameters on failure strength of rock crusher jaw plates using theoretical and Finite Element analysis to simulate the stresses and deflections of different geometries ( sharp, taper and rectangular jaw plate profiles).The measured dimensions of existing jaw plate are taken from Gondar PLC of rock crusher industry. The current jaw plate geometry is tapered at the surface finish. This geometry is less efficient during the productivity of the company due to the consequent change of the plates. After checking of the failure duration of the geometries the good stress and deflection relive profiles are selected. The rectangular jaw plate geometries were reduced the stress and deflections by 45% than the tapered jaw plate geometry. The jaw plate stresses and deflections are checked by material substitution of high manganese steel and white cast iron with the same geometries selected for the comparison using analytical equation and ANSYS simulated. High manganese steel has higher failure strength than white cast iron.