The invention discloses a waterproof guide wheel. The waterproof guide wheel comprises two guide wheel bases (2) and a guide wheel body. The guide wheel body is arranged between the two guide wheel bases (2) and composed of an impeller (1) and a guide wheel shaft (7). The guide wheel shaft (7) is supported by bearings (9) in the guide wheel bases (2), the two ends of the guide wheel shaft (7) extend out of the bearings (9) respectively, the portions, located outside the bearings (9), of the two ends of the guide wheel shaft (7) are respectively provided with a pressing plate (4) and a nut (5) in sequence, and the pressing plates (4) press the bearings (9) through the nuts (5). The guide wheel shaft (7) is closely sleeved with waterproof sealing washers (8), and the waterproof sealing washers (8) seal the gaps between the guide wheel shaft (7) and the guide wheel bases (2) and rotate along the guide wheel body. The end of each guide wheel base (2) is provided with an overflow hole (3), and the tail end of each overflow hole (3) is provided with a waterproof groove (6). The waterproof guide wheel has the advantages of being good in waterproof effect, long in service life and high in cutting accuracy.