Board material and a preparation method thereof

A board material, comprising:

• an inorganic board, the inorganic board comprises a plant fiber and an inorganic material, in which the mass ratio of the inorganic material to the plant fiber is in the range of 1.2 to 1.5;
• the raw material components of the inorganic material comprise a magnesium sulfate and a magnesium oxide, the mass ratio of the magnesium sulfate to the magnesium oxide is in the range of 0.4 to 0.5;
• the raw material components of the inorganic material further comprise a magnesium chloride and a modifier, the mass ratio of magnesium chloride to magnesium oxide is in the range of 0.09 to 0.15;
• the modifier is citric acid;
• in the raw material components of the inorganic material, the mass ratio of the modifier to the magnesium chloride is in the range of 0.025 to 0.045;
• the 24 h water-absorbing thickness swelling of the inorganic board is less than or equal to 3%,
• the raw material components of the inorganic material comprise:
• 2% to 6% magnesium chloride, based on the total weight of the raw material components of the inorganic material, 17% to 23% magnesium sulfate, based on the total weight of the raw material components of the inorganic material;
• and 40% to 48% magnesium oxide, based on the total weight of the raw material components of the inorganic material.