The thermodynamic properties such as entropy in a microscopic system under an applied external field can decrease or increase in a stochastic process through random fluctuations of microscopic degrees of freedom. Theses fluctuations in microscopic level which lead to probability distribution of entropy production with a symmetry around an average are recognized in fluctuation theorems . The density probability distribution of entropy production exponentially narrows with the increase of the system's size and arrow of time. The average value resulted from these random fluctuations through arrow of time statistically increases the entropy of the macroscopic system .