Abstract: The invention relates to an electric housing device having an adjustable span, comprising a main body portion, a winding cord, and a first moving part and a second moving part close to the two ends of the main body portion. The main body portion is provided with a driving device, and the bottom of the main body portion is provided with two parallel slide rails which slide along the length direction of the main body portion. The two slide rails extend towards the first moving part and the second moving part respectively and are fixed to the bottoms of the corresponding moving parts. The main body portion and the first moving part, and the main body portion and the second moving part are respectively provided with through grooves corresponding to the two slide rails, each through groove is located on the outside of the corresponding slide rail, each slide rail is slidably provided with a central running pulley, and the top of each central running pulley extends out from the corresponding through groove.