A temperature-resistant calcium-resistant water-based drilling fluid for oil and gas reservoir protection and a use thereof is provided. The water-based drilling fluid contains a filtrate reducer and a plugging agent, wherein the filtrate reducer is a copolymer that contains structural units represented by formula (1), structural units represented by formula (2), and structural units represented by formula (3), wherein, the mass ratio of the structural units represented by formula (1) to the structural units represented by formula (2) to the structural units represented by formula (3) is (0.1-0.2):1:(0.05-0.1), and the number-average molecular weight of the copolymer is 10,000-100,000, the plugging agent is acrylamide-diallyldimethylammonium chloride copolymer modified graphene. The water-based drilling fluid described can exhibit excellent filtrate reducing, plugging, temperature-resistant, anti-collapsing, and reservoir protective performance when it is applied in well drilling in deep high-temperature wells.