The invention provides a transmission device for a hybrid vehicle, which comprises a first differential-velocity gear set comprising at least three rotary parts, a second differential-velocity gear set comprising at least three rotary parts, a first electric generator consecutively connected with the first differential-velocity gear set rotary parts except the rotary parts connected to the rotary part of an engine and the parts selectively connected with each other, a second electric generator consecutively connected with the second differential-velocity gear set rotary parts which are consecutively connected with the rotary parts of the first differential-velocity gear set, a first fixing mechanism for limiting the second differential-velocity gear set rotary parts except the rotary parts connected to an output part and the second electric generator to rotate, and a second fixing mechanism for limiting the second differential-velocity gear set rotary parts consecutively connected with the second electric generator to rotate.