The famous energy equation for the steady flow of ideal fluids, the Bernoulli equation, has contributed greatly to the fluid mechanics since its publication. Based on the connotation of Bernoulli equation, this paper discusses its successful application in hydrostatics, steady orifice outflow, pitot tube velocity measurement, venturi flow and airfoil flow. At the same time, the modeling of the local following fluid particles is suggested by Bernoulli equation. It is summarized by Euler as the flow field method describing the fluid motion, which is the basic basis for deriving the Euler equations and the NS equations. It also laid the foundation for the establishment of the later turbulence theory, boundary layer theory, aerodynamic noise and other theories.