The invention discloses warm mixed hard asphalt. The asphalt comprises a warm mixing agent and basic asphalt. A preparation method of the warm mixing agent comprises carrying out hydro-conversion on an F-T synthesis product having n-alkane weight content of 85% or more as a raw material and carrying out sweating on the hydrogenation product. Airflows pass through a material layer and carry away a liquid component in the sweating process so that separation effects of a solid component and the liquid component are improved and a separation rate is accelerated. Gas produced by inorganic salt decomposition forms micro-spaces in the material layer so that the liquid component fast outflows. The warm mixed hard asphalt contains the warm mixing agent, realizes warm mixing, reduces the amount of harmful gas and improves aging resistance.