Lightweight foam concrete

The invention discloses lightweight foam concrete. The foam concrete comprises 10-20 parts of a solid adsorbent, 900-950 parts of Portland cement, 30-45 parts of gypsum powder, 0.2-1.0 part of polyformaldehyde fiber, 15-25 parts of a foaming agent, 35-55 parts of peroxide with a protective film and 400 parts of water. A preparation method comprises the following specific preparation steps: 1, adding the solid adsorbent into water for dissolving, then sequentially adding the Portland cement, the gypsum powder and the polyformaldehyde fiber into the solution, and continuously stirring until uniform gel is formed for later use; 2, preparing foams from the foaming agent, adding the oxide product with the protective film into the foams, and performing uniform stirring; and 3, adding the foam material in the step 2 into the gel prepared in the step 1, performing uniform mixing, pouring the mixture into a mold for molding, and performing curing for 5-8 days to obtain a light foam concrete finished product capable of