The invention discloses a composite high-performance asphalt modified high modulus agent and preparation and application methods thereof. The composite high-performance asphalt modified high modulus agent and the preparation and application methods thereof are characterized in that a main component A and an auxiliary component B are separately prepared, and the main component A and the auxiliary component B are applied to asphalt modification in a composite mode. According to the mass ratio of ingredients in each component, 70% to 90% of reclaimed polyethylene (PE), 0.1% to 8% of nano-magnesium hydroxide, 0.5% to 15% of modifying agents and 0.5% to 12% of adhesive resins are uniformly stirred in a blender mixer, discharged and packaged to obtain the main component A, and 15% to 30% of styrene-butadiene-styrene (SBS) thermoplastic elastomers are dissolved in 70% to 85% of peptizing agents to prepare 25% to 30% of SBS mucilage mother liquor to obtain the auxiliary component B. The composite high-performance asphalt modified high modulus agent and the preparation and application methods thereof aim to achieve waste recovery and provide the composite high-performance asphalt modified high modulus agent through a simple and practicable method, performance index of common modified asphalt can be achieved, simultaneously the universality is achieved, and compared with common asphalt modifiers, the composite high-performance asphalt modified high modulus agent has competitive advantages in terms of cost of manufacture.