The utility model discloses a cable protective sleeve applied to occasions such as mechanism cases and switch cabinets, in particular an adjustable secondary cable protective sleeve. The adjustable secondary cable protective sleeve comprises a cable protective sleeve and a cable protective sleeve moving section which is sleeved on the cable protective sleeve, wherein the lower section of the cable protective sleeve moving section is provided with an external thread; the cable protective sleeve moving section is connected with a cable protective sleeve locking section with an internal thread through the external thread in a matching mode and can be fixedly locked with the cable protective sleeve; and the upper end of the cable protective sleeve moving section and the cable protective sleeve have equal diameter. By adoption of the structure, the length of the secondary cable protective sleeve can be adjusted in a certain range in the construction process, so that the secondary cable protective sleeve is convenient to mount; and moreover, the secondary cable protective sleeve is not required to be cut during construction, the problem of processing difficulty is solved, unsafe factors such as the injury of workers caused by electric cutting pieces in the processing process are reduced, and the protective sleeves made of plastic materials and steel pipes are corrosion-resistant, durable and high in insulating strength.