In this thesis we look at different aspects of an effective field theory treatment of gravity. The effective field theory method entitles us to compute the long range quantum corrections to general relativity and to avoid the main issue about the field theory of gravity which is its non-renormalisability. We first expose briefly the main tools we use in the following parts: we derive the effective field theory rules, we show the main principles of the unitarity methods with whom we will reduce the loop amplitudes computation to on-shell tree amplitudes manipulations. Finally we make an analysis on the Feynman integrals at all loop showing why and how classical terms can be extracted from Feynman integrals. Then we apply these tools to the computation of the quantum correction of the bending of light by a gravitational source, getting a correction in the relation between the bending angle and the impact parameter. We aslo show how to deal with infrared divergences. In the last part, we attack the two-loop problem and we show how to derive all the integrals. At the end, we successfully extract the second post-newtonian correction.