Equivalence of Descriptions of Gravity In Both Curved and Flat Space-time

It is proved in the manuscript that as long as the proper coordinate transformation is introduced,, the equations of geodetic lines described in curved space-time can be transformed into the dynamic equations in flat space-time, that is to say, the Einstein theory of gravitation and other theories based on the curved space-time can be identically transformed into flat space-time to describe. As an example, the Schwarzschild solution of the spherical symmetry gravitational field is transformed into flat space-time to study. The results show that there exists no any singularity in the all processes and the whole space-time including at the point r=0. So it seems more rational to discuss the problems of gravitation in flat space-time.