Euler's profound knowledge, endless creative energy and unprecedented rich works are amazing! He published papers from the age of 19 to the age of 76, and has written countless books and papers for more than half a century. Up to now, Euler's name can be seen in almost every mathematical field, from Euler line of elementary geometry, euler theorem of polyhedron, Euler transformation formula of solid analytic geometry, Euler solution of quartic equation to Euler function in number theory, Euler equation of differential equation, Euler constant of series theory and Euler equation of variational method. Euler formula of complex variable function, etc. , is countless. His contribution to mathematical analysis is even more original. Introduction to infinitesimal analysis is his epoch-making masterpiece, and mathematicians call him "the embodiment of analysis" at that time.