An olaparib oral sustained and controlled release pharmaceutical composition, which comprises an olaparib in an improved dissolution form; and a release rate adjusting matrix polymer, wherein the olaparib oral sustained and controlled release pharmaceutical composition has a steady-state plasma concentration valley value C min,ss of 0.2 to 4 μg/mL; and a steady-state plasma concentration peak value C max,ss of 0.8 to 15 μg/mL, wherein the olaparib in an improved dissolution form is selected from the group consisting of an olaparib salt, an olaparib co-grinding mixture, an olaparib nanocrystal and an olaparib solid dispersion; and the release rate adjusting matrix polymer is selected from the group consisting of a cellulose derivative, a starch or a derivative thereof, an alginate, an acrylic or methacrylic acid derivative, a polyethylene oxide, a gum, and a carbohydrate-based polymer, preferably, one or a combination of two or more selected from the group consisting of hydroxypropyl cellulose, polyethylene glycol, hypromellose, methylcellulose, hydroxyethylcellulose, ethylcellulose, cellulose acetate, sodium alginate, povidone, copolyvidone, acrylic resin, carbomer, preferably one or a combination of two or more selected from the group consisting of hydroxypropylcellulose, sodium alginate, hypromellose, and carbomer; preferably, the olaparib salt is selected from the group consisting of hydrochloride, besylate, sulfate, maleate, and camphorate; preferably, the olaparib co-grinding mixture consists of the pharmaceutically active ingredient olaparib, a matrix polymer for solubilization and other additives, and is prepared by co-grinding the components; in the co-grinding mixture, based on the total weight of the co-grinding mixture, the olaparib is 5 to 60 wt%, preferably 20 to 40 wt%, and the matrix polymer for solubilization is 40 to 95 wt%, preferably 40 to 80 wt%, the other additives is 0 to 15 wt%, preferably 0.2 to 10 wt%; preferably, the olaparib nanocrystal consists of the pharmaceutically active ingredient olaparib, a matrix polymer for solubilization, and/or other additives, and is obtained by prepared the components into nanosized particles by high pressure homogenization or coprecipitation; in the olaparib nanocrystal, based on the total weight of the olaparib nanocrystal, the olaparib is 10 to 99 wt%, preferably 20 to 50 wt%; the matrix polymer for solubilization is 1 to 75 wt%, preferably 1 to 65 wt%, and the other additives are 0 to 10 wt%, preferably 0 to 5 wt%; preferably the nanocrystal has a particle size of 50 to 1000 nm; preferably, the solid dispersion consists of the pharmaceutically active ingredient olaparib, a matrix polymer for solubilization and other additives, and is prepared by solvent evaporation or melt extrusion, in the solid dispersion, based on the total weight of the solid dispersion, olaparib is 5 to 50 wt%, preferably 10 to 40 wt%, more preferably 20 to 40 wt%, the matrix polymer for solubilization is 45 to 95 wt%, preferably 50 to 80 wt%, and the other additives are 0 to 12 wt%, preferably 0 to 10 wt%; preferably, the matrix polymer for solubilization is one or a combination of two or more selected from the group consisting of povidone, copovidone, polyoxyethylene, Soluplus®, hypromellose phthalate, hydroxypropylcellulose succinate acetate, polyethylene glycol, poloxamer, polymethacrylic acid, polyethyl acrylate, 2-hydroxypropyl-β-cyclodextrin, hypromellose, polymethacrylate, hydroxypropyl cellulose, cellulose acetate phthalate, and other pharmaceutically acceptable polymers for solubilization; preferably, the other additives are one or a combination of two or more selected from the group consisting of pharmaceutically acceptable surfactants, a lubricant, a colloidal silica, a plasticizer, wherein the surfactant is preferably polyethylene glycol stearate or sodium lauryl sulfate.