An adjustable fan damping apparatus for exerciser includes a casing having an annular chamber defined therein and an annular intake structure is disposed to an inner side of the annular chamber. A centrifugal impeller is rotatably received in the annular chamber. Multiple adjust blades is pivotally mounted onto the annular intake structure and surrounds the annular intake structure, wherein each adjust blade has two pivots longitudinally extending from two opposite ends of the adjust blade and a driven element extending from one side of then adjust blade where the two pivots extends. A drive device is connected to the driven element of each of the multiple adjust blades. The drive device includes a driving element is rotatably coupled with the driven element of each of the multiple adjust blades for simultaneously driving the multiple adjust blades in a same angle relative to the annular intake structure.