Considering the influence of the inertia item on temperature distribution of multidisk friction pairs in hydroviscous drive (HVD), transient temperature models are derived with the aim of revealing the effect of engagement pressure, lubricant viscosity, viscosity–temperature correlation, surface roughness and the ratio of inner and outer radius of disks on temperature distribution. The results indicate that unsteady temperature gradient can be avoided by matching the suitable materials for multidisk friction pairs. The average temperature for the case of neglecting the inertia item is lower than that of the case of including the inertia item. It is shown that during the soft-start, the temperature along the radial direction achieves its peak value near the outlet and keeps decreasing along the axial direction; while after the engaging process, the temperature distribution tends to be uniform. It is also shown that the decrease of engagement pressure, surface roughness and the ratio of inner and outer radius of disks can reduce temperature gradient effectively as well as the increase of lubricant viscosity. The average temperature for the case of including the viscosity–temperature correlation is much higher than that for other cases.