Abstract: For the numerical simulation of non-stationary fluctuating wind velocity, the critical factor is to obtain time-varying power spectra (referred here to as the TVPS). According to the theory of evolutionary power spectra (referred to as the EPS), TVPS, namely EPS, can be acquired through this way using a deterministic modulating function (referred to as the DMF) to modulate a known power spectra of stationary fluctuating wind velocity such as Kaimal spectra, Davenport spectra or Simiu spectra. But there is not a DMF that can be universally acknowledged currently, so that the simulation of non-stationary fluctuating wind velocity can be scarcely paid attention to. In order to acquire a DMF to stimulate the non-stationary fluctuating wind velocity, firstly this paper assumes that a non-stationary fluctuating wind velocity during the time is made of segments of stationary fluctuating wind velocity with a very short time ; then, TVPS can be obtained by connecting each power spectra from segments of stationary fluctuating wind velocity when ; finally, DMF has been deduced through the relation that TVPS is equal to EPS, and the simulations of the non-stationary wind velocity for three spatial points has been carried out using harmony superposition method.