The present invention relates to a heavy oil hydrogenation protection catalyst, preparation and applications thereof. According to the catalyst, Al2O3 or SiO2-containing Al2O3 is adopted as a carrier; a carrier pore volume is 0.98-1.15 ml/g; a specific surface area is 340-380 m<2>/g; pore distribution is as the follow: the amount of the pore volume of pores with a pore diameter of less than 5 nm is 10-15% of the amount of the total pore volume, the amount of the pore volume of pores with a pore diameter of 5-15 nm is 50-55% of the amount of the total pore volume, and the amount of the pore volume of pores with a pore diameter of more than 15 nm is 25-40% of the amount of the total pore volume; the catalyst is loaded with nickel-molybdenum-sulfur, nickel-tungsten-sulfur, molybdenum sulfide, tungsten sulfide, cobalt-molybdenum-sulfur, cobalt-tungsten-sulfur, nickel-cobalt-molybdenum-sulfur, nickel-cobalt-tungsten-sulfur or cobalt-molybdenum-nickel-tungsten, and the loaded material is combined with Ni2P to form the composite catalyst. The catalyst has characteristics of suitable pore size, high metal melting ability, small active ingredient scale, good dispersity and high catalyst activity, and is suitable for heavy oil and heavy oil protection catalysts.