The invention discloses a heat-resisting lyophilized protectant for chicken newcastle disease and chicken infectious bronchitis dual living vaccine and a preparation method thereof. The heat-resisting protectant consists of solution A and solution B in a volume ratio of 1:1, wherein the solution A consists of the following compositions: 4 to 6g of sucrose, 3 to 5g of polypeptone, 1 to 3 g of D-sorbitol and the balance of water for injection in each 100 milliliters of the solution A; and the solution B consists of the following compositions: 3 to 5g of polyvinylpyrrolidone, 0.5 to 1.5g of L-arginine and the balance of water for injection in each 100 milliliters of the solution B. The heat-resisting lyophilized protectant has the advantages of good heat resistance, capacity of effectively protecting the living vaccine, simple formula components and preparation method, low production cost, and mass production and the like. The heat-resisting lyophilized protectant can ensure that the chicken newcastle disease and chicken infectious bronchitis dual living vaccine is preserved for more than 24 months at a temperature of between 2 and 8 DEG C.