Interface bonding agent for building outside wall insulation board and preparation method thereof

The invention discloses an interface bonding agent for a building outside wall insulation board and a preparation method thereof. The interface bonding agent comprises the following components: magnesium oxide and an ultramicro building material highly-efficient additive. The invention further discloses a method for preparing the interface bonding agent and an application method thereof. The interface bonding agent has excellent permeability and bonding performance, can firmly bond a fire-resistant and anti-aging material on the insulation board, and can also effectively improve the density and compressive strength of the insulation board, so that the service life of the insulation board is obviously prolonged, and the insulation performance, fire resistance and anti-aging performance of the insulation board are improved.