Abstract: A mattress protector includes an upper layer, a lower layer, a side layer linking edges of the upper and lower layers, and a plurality of joint members. The side layer has a top periphery and a bottom periphery, which abut the upper and lower layers, respectively. Each joint member deployed around the side layer is spaced from the top periphery of the side layer by a distinct distance. A section of the side layer can be double folded in a height direction for development of a first folding portion and a second folding portion. The mattress protector is able to tightly wrap a mattress featuring a distinct thickness when the joint members join the side layer to fix the first and second folding portions of the side layer. The present invention further provides a method to wrap a mattress with the mattress protector.