2018-11-082018-11-082007http://hdl.handle.net/123456789/13485athesis submited for the degree bh.Abstract In this research we talk about symmetry of D.E"‘ via symmetry of variation and we write the variation by modern methods 0lD.E"‘. So we utilize methods of global analysis such as differential geometry . ln this research we introduce the theory of fiber bundles .We give application ol" fiber bundles : Gauge theory and variational principles .Als0 we formulate Euler — Lagrange equations by three methods ( without coordinate ) our treatment is global since we employed fiber bundle formulation .the thory of vanianal symmetry grobThesis