The utility model discloses a driving structure of a ratchet wrench, comprising a wrench body, a ratchet wheel, a ratchet block and a spring. The wrench body is provided with an imbedding hole penetrating up and down, the wall surface of the imbedding hole is at least convexly provided with a containing chamber, the containing chamber is provided with a top face, a bottom face opposite to the top face and a vertical wall connected between the top face and the bottom face, and the vertical wall is also provided with a location part. The ratchet wheel is pivoted in the imbedding hole and is provided with a driving hole and an outer tooth part annularly arranged at the periphery. The ratchet block is arranged in the containing chamber and is provided with a back face adjacent to the vertical wall of the containing chamber and a front face adjacent to the outer tooth part of the ratchet wheel, wherein the back face is provided with a location unit, a gap is formed between the left and right sides and the vertical wall of the containing chamber, the left half part of the front face of the ratchet block is provided with blocking teeth which can be engaged with the outer tooth part of the ratchet wheel, and the right half part is provided with a flee region which can be separated from the outer tooth part of the ratchet wheel. One end of the spring is limited at the location part, and the other end is limited to the location unit so that the ratchet block can be coupled in the containing chamber through the spring. The utility model has the characteristics of long service life and wide application environment.