The invention discloses an asphalt composition. The asphalt composition comprises matrix asphalt, a composite additive, a cationoid emulsifier and a polymer modifier, wherein on the basis of 100 parts by weight of the matrix asphalt, the contents of the composite additive, the cationoid emulsifier and the polymer modifier are, by weight, 0.1 to 5 parts, 1.5 to 5 parts and 2 to 10 parts, respectively; the composite additive contains rosin acid and alkylphenol; and the cationoid emulsifier contains an imidazoline emulsifier. The invention also provides emulsified asphalt formed by the asphalt composition and a preparation method thereof, and an asphalt mixture and application thereof. The asphalt mixture provided by the invention is sufficient in mixing time and high in early strength; each performance index of the asphalt mixture meets or exceeds requirements prescribed in the technical specification JTG/T F40-2004 for common mixed micro-surfacing emulsified asphalt; and the asphalt mixture is applicable to micro-surfaces of pavements of tunnels and other pavements serving in low-temperature high-moisture environments.