Abstract: A seat rod of a bicycle, comprises a seat rod having an assembly portion at a top end thereof; a lateral side of the assembly portion having a first sliding groove; and a top of the assembly portion having a second sliding groove which is communicated to the first sliding groove; a connecting unit for clamping a cushion of a bicycle; the connecting unit being installed with a pin so that the connecting unit is slideable installed in the second sliding groove; and a driving unit including a handle and an eccentric rod inserted into the first sliding groove. When the handle of the driving unit is driven, the handle will at a position of releasing or tightening, then the driving unit slides along the first sliding groove and the connecting unit is driven to slide.