Check the care label attached to your slipcover and follow the manufacturer's recommendations, especially if the tag says "dry clean only." If the care tag indicates the slipcover is machine-washable, or if it is made of cotton or another washable fabric, it's OK to proceed.
Apply a laundry stain pretreater or dish-washing liquid to any stains, lightly rubbing the cleansing agent into the stained area.
Place the slipcover into your washing machine, leaving it right side out and closing any open zippers. Launder in cold to warm water with laundry detergent.
Dry your slipcover on a low-heat or permanent press setting, depending on your slipcover's care recommendations, for 10 to 15 minutes.
Remove your slipcover from the dryer while still a little damp and fit it onto your sofa. This will help it to better conform to your sofa’s size and shape, as well as reduce wrinkles.
Iron wrinkles out of the hem or corners of the slipcover, if desired. Don't iron other portions while the slipcover is damp or you might stretch the fabric and misshape it.