A multi-function oar has an oar blade, a large-diameter tube, and a small-diameter tube. The oar blade has a tube-connecting portion. The tube-connecting portion has a through axial hole. The large-diameter tube is movably inserted in the axial hole. The axial hole has an upper positioning portion and a lower positioning portion for positioning the large-diameter tube, thereby changing the overall length of the oar. The large-diameter tube has a first check valve. The first check valve has a bail opening. The small-diameter tube is provided with a second check valve and an operating member having a water outlet, so as to bail water and drain water.