  The principle of entropy increase is not only the basis of statistical
mechanics, but also closely related to the irreversibility of time, the origin
of life, chaos and turbulence. In this paper, we first discuss the dynamic
system definition of entropy from the perspective of symbol and partition of
information, and propose the entropy transfer characteristics based on the set
partition. By introducing the hypothesis of limited accuracy of measurement
into the continuous dynamical system, two necessary mechanisms for the
formation of chaos are obtained: the transfer of entropy from small scale to
macro scale (i.e. the increase of local entropy) and the dissipation of macro
information. The relationship between the local entropy increase and Lyapunov
exponent of dynamical system is established. And then the entropy increase and
abnormal dissipation mechanism in physical system are analyzed and discussed.
