Composition used as board, ceiling board and preparation method of ceiling board

The invention provides composition used as a board. The composition comprises a liquid raw material and a solid raw material, wherein the solid raw material comprises fly ash, slag and a pore-forming agent; the liquid raw material comprises alkali hydroxides and sodium silicate; the slag comprises SiO2, Al2O3 and CaO. According to the composition, main components, namely, SiO2 and Al2O3, of the slag and the fly ash react with the liquid raw material, a material adopting a three-dimensional network structure can be formed, the strength of the board can be significantly enhanced, CaO of the slag reacts with the sodium silicate of the liquid raw material, calcium silicate is produced, and the consolidation strength can be further enhanced. Besides, the board made of the composition has functions of moisture absorption, formaldehyde absorption and sound absorption. The invention further provides a ceiling board and a preparation method thereof. Experimental results indicate that the bending strength of the ceiling board made of the composition is 17.7 MPa, and the formaldehyde purification ratio is 30%-67%.