The flow behavior of the Mg-Zn-Zr-Y alloy was investigated by hot compressive test using Gleeble thermal simulator in the temperature range of 573~723K and strain rate range of 0.001~1s_-1. The results show that the flow stress is significantly affected by both deformation temperature and strain rate. The flow behavior were characterized by the SsaturationSnonlinearity and positiveSskewness occur simultaneously, and the flow stress increases with either decreasing deformation temperature or increasing strain rate. The average activation energy(Q=152.307 KJ.mol_-1), and stressSexponent(n=5.521)for the hot deformation have been determinded to be using the Arrhenius-type and Zener-Holloman equations. A nonlinear flow model and its constitutive equation have been established and employed for studying the deformation behavior. Meanwhile,ScalculationSresults of constitutive equations were comparedSwith experimentalSresults; the level of data match depends on temperature and strain rate. TheSsaturationSnonlinearity of flow behavior in the alloy was satisfactorily described, theStheoretical calculating valuesSmatchSwellSwithSthe experimentalSSvalues. Furthermore, the calculation values of flow stress will be bigger than its experimental values with the positiveSskewness of flow behavior , and as the peak strain of calculationSresults ahead. Research show this constitutive equations effectively depict the flow behaviors of hot compression deformation, however, it is more specifically suited to high deformation temperature(＞623K) and low strain rate(＜0.01 s _-1).