The invention discloses a swing arm type speed reducer base structure which comprises a base used for bearing a speed reducer, swing arms movably connected to the base, hydraulic assemblies and an oil tank. The hydraulic assemblies are connected to the ends, away from the base, of the swing arms. The oil tank is arranged on one side of the base. The hydraulic assemblies are connected to the oil tank through pipelines. By means of the swing arm type speed reducer base structure, a speed reducer is installed on the base, and therefore the hydraulic assemblies can be used for achieving ascending and descending of the position of the speed reducer, the running speed of large equipment is reduced through the speed reducer, barring, checking and maintaining are achieved under the dynamic condition of the large equipment, and the use safety of the large equipment is ensured. Meanwhile, the installation positions of the hydraulic assemblies relative to the base are adjusted by adjusting the connecting angles between the swing arms and the base, and therefore the swing arm type speed reducer base structure can be installed in a non-flat place, meanwhile, the contact area between the whole speed reducer base structure and the ground can be enlarged, and running of the speed reducer is more stable.