The atmospheric heat dispersion of magnesium alloys AZ80、AZ31、ZK60 and aluminum alloys AA6082 were measured. It was apparently that the thermal dispersion curves of the columnar model can be exponential fitted as T=T0+ΔT0·exp(-t/A0). The result shows that the solution treatment can make the thermal conductivity of the magnesium alloys decrease. However, the solutionizing plus aging treatment can make the thermal conductivity increase. The relationship between ΔT/T and the heat dispersion rate was also studied. The heat dispersion rate of high columns (60mm) is about two times that of low columns (20mm) in the condition of forced air convection, while there is no obvious difference in the condition of natural convection. Moreover, the dispersion properties of these alloys can be evidently dived into two regions by ΔT/T in natural convection. There was no much difference among AZ80、AZ31、AA6082 alloys when 0.05<ΔT/T<0.25 (20~120℃), while the AZ80 and AZ31 exhibited more preferential performance than AA6082 alloys when 0.25<ΔT/T<0.45 (120~220℃).