Additive agent suitable for calcium silicate board

The invention relates to the technical field of building materials and especially relates to an additive agent suitable for calcium silicate boards, which is prepared from following raw materials, by weight, 2-6 parts of sodium aluminate, 1-4 parts of quick lime, 2-5 parts of gypsum and 2-6 parts of sodium silicate or potassium silicate. The additive agent is toxic-free and pollution-free, can greatly increase adding quantity of fly ash, mineral residue and such waste residues in the calcium silicate boards, significantly improves strength, heat insulation and dampness proofing performance of the calcium silicate boards, can reduce cost, and is easy and convenient to use.