Abstract: Aimed at the problem that the abundance level fluctuations of galactose affect the yeast phenotypes directly or indirectly, it is necessary to decode the regulation mechanism of the multi-scale noise mediated Gal4 gene coupling positive and negative feedback loops. In the report, the multi-source colored noise was introduced, an equivalent Fokker-Planck equation was constructed, the steady state probability distribution function and the mean first passage time was calculated, the relevant dynamic indicators were analyzed to reveal the system’s dynamic behavior, a sensitivity function was defined to evaluate the influence of each regulatory source from the perspective of systems theory. The results indicated that the galactose abundance level can directly modulate the stochastic bifurcation of the Gal4 gene expression system, and under the induction of colored noise, the changes of noise intensity and its autocorrelation time alter the peak structure of the probability distribution function and state-switching time, and the effects of multiplicative noise on the system was greater than that of additive noise.