The invention relates to the field of vehicle machines, in particular to a vehicle rotating load stable transmission device. The vehicle rotating load stable transmission device comprises a shell, a transmission assembly, an intermediate assembly and an adjusting assembly, wherein the shell is used for supporting and mounting remaining components, the transmission assembly is a planetary gear mechanism with a sun wheel as an input wheel, and the planetary gear mechanism is externally engaged with an output wheel through a big sun wheel so as to achieve power output; the intermediate assembly is used for converting rotating of a planetary wheel set into horizontal constant-speed reentry movement, and the movement is transmitted to the adjusting assembly; and the adjusting assembly utilizesfrictional resistance to adjust the rotating state of a planetary wheel. According to the vehicle rotating load stable transmission device, when input is stable, the planetary wheel set does not participate in adjusting; when input fluctuates, fluctuation of the vehicle rotating load stable transmission device can be reduced through the planetary wheel set; when the output end is excessively largein load, the input end can be prevented from being overloaded; when overloading occurs, the situation that the reverse rotating speed of the output end is excessively high and consequently out of control occurs can be prevented; and the device is simple in structure and low in cost.