A transmission assembly for a doll includes a first driving device having a rotation sleeve adapted to be rotatably received in the top base and a twist driving element connected to the rotation sleeve to drive the rotation sleeve to twist to the right and to the left and a second driving device including a first motor, a first gear box operably connected to the first motor via a first transmission element, a first eccentric roller in connection with the first gear box and having an axle extending out of the first eccentric roller to be rotatably received in the rotation sleeve so as to drive the top base and the casing up and down and a second eccentric roller having a first linkage extending out of the second eccentric roller to drive the top base and the casing back and forth.