A softness-adjustable mattress, including an outer lining, an outer lining zipper, and a bottom lining, wherein: the bottom lining is positioned on the outer lining, the outer lining zipper is positioned between the outer lining and the bottom lining, a lying-down mechanism is mounted on an inner lower wall face of the outer lining, and an inflation mechanism is mounted on the lying-down mechanism; wherein the lying-down mechanism comprises: an inner lining, an inner lining zipper, and wavy cotton; the wavy cotton being positioned on the inner lower wall face of the outer lining, the inner lining being positioned on the wavy cotton, and the inner lining zipper being positioned between the inner lining and the outer lining; wherein the inflation mechanism comprises a first inflation structure and a second inflation structure; the first inflation structure being positioned on the inner lining and inside of the outer lining, and the second inflation structure being inserted into an inner left side of the first inflation structure; wherein the first inflation structure comprises: a pair of air cushions of the same structure, a pair of first spongy strips of the same structure, a spongy cushion, a second spongy strip and a third spongy strip; the pair of the first spongy strips being positioned on the inner front and back wall faces of the outer lining and on the inner lining, the second spongy strip being positioned on an inner right wall face of the outer lining and on the inner lining, the third spongy strip being positioned on an inner left wall face of the outer lining and on the inner lining, the pair of the air cushions being positioned between the pair of the first spongy strips, and the spongy cushion being positioned on the pair of the air cushions; wherein the second inflation structure comprises a first conduit, an inflation controller, a second conduit and palm-substituent cotton; the inflation controller being inserted into an inner rear part of the third spongy strip, a trapezoid groove being provided on an inner wall face of the third spongy strip and at the front part of the inflation controller; the first conduit being provided on a front wall face of the inflation controller and inside of the trapezoid groove; the first conduit being connected with the air cushion close to the front part, the second conduit being positioned on the front wall face of the inflation controller and on the first conduit, the second conduit being inserted inside of the trapezoid groove and being connected with the air cushion close to the rear part, the palm-substituent cotton being positioned on the inflation controller, and the palm-substituent cotton being connected with an inner wall face of the third spongy strip. the bottom lining is positioned on the outer lining, the outer lining zipper is positioned between the outer lining and the bottom lining, a lying-down mechanism is mounted on an inner lower wall face of the outer lining, and an inflation mechanism is mounted on the lying-down mechanism; wherein the lying-down mechanism comprises: an inner lining, an inner lining zipper, and wavy cotton; the wavy cotton being positioned on the inner lower wall face of the outer lining, the inner lining being positioned on the wavy cotton, and the inner lining zipper being positioned between the inner lining and the outer lining; wherein the inflation mechanism comprises a first inflation structure and a second inflation structure; the first inflation structure being positioned on the inner lining and inside of the outer lining, and the second inflation structure being inserted into an inner left side of the first inflation structure; wherein the first inflation structure comprises: a pair of air cushions of the same structure, a pair of first spongy strips of the same structure, a spongy cushion, a second spongy strip and a third spongy strip; the pair of the first spongy strips being positioned on the inner front and back wall faces of the outer lining and on the inner lining, the second spongy strip being positioned on an inner right wall face of the outer lining and on the inner lining, the third spongy strip being positioned on an inner left wall face of the outer lining and on the inner lining, the pair of the air cushions being positioned between the pair of the first spongy strips, and the spongy cushion being positioned on the pair of the air cushions; wherein the second inflation structure comprises a first conduit, an inflation controller, a second conduit and palm-substituent cotton; the inflation controller being inserted into an inner rear part of the third spongy strip, a trapezoid groove being provided on an inner wall face of the third spongy strip and at the front part of the inflation controller; the first conduit being provided on a front wall face of the inflation controller and inside of the trapezoid groove; the first conduit being connected with the air cushion close to the front part, the second conduit being positioned on the front wall face of the inflation controller and on the first conduit, the second conduit being inserted inside of the trapezoid groove and being connected with the air cushion close to the rear part, the palm-substituent cotton being positioned on the inflation controller, and the palm-substituent cotton being connected with an inner wall face of the third spongy strip.