Two-gear planetary gear shifting speed reducer

The utility model provides a two-gear planetary gear shifting speed reducer, and relates to the technical field of speed reducers. The second-gear planetary gear shifting speed reducer comprises a planetary speed reducer and a gear shifting sliding sleeve. An inner gear ring bracket of the planetary reducer is provided with a first external spline; a gear shifting support is fixedly installed on a gear carrier of the planetary reducer and provided with a second outer spline. A planet carrier external spline of the planetary reducer is connected with a spline housing; a third external spline is arranged on the outer wall of the spline housing; an inner spline is arranged on the inner wall of the gear shifting sliding sleeve; when the gear shifting sliding sleeve is close to the gear shifting support, the gear shifting sliding sleeve is in spline connection with the first external spline and the second external spline at the same time. When the gear shifting sliding sleeve is far away from the gear shifting sup