Prime objective of this article is to Discuss on Variation of Parameters. Here explain Variation of Parameters in proper examples and theory. For the differential equation: a (x)y”+ b (x)y” + c (x)y” = d (x); the strategy of undetermined coefficients works as long as the coefficients a, b, and c are constants and also the right‐hand term d( x) is of the special form. If these restrictions do not apply to a granted non homogeneous linear differential formula, then a more powerful means of determining a particular solution should be applied: the method known as variation of parameters.