A self-drilling screw comprising: a head having a bottom surface; a shank extending longitudinally from said bottom surface of said head and defining a central axis, wherein said shank forms a leading section located opposite to said head, said leading section including a drill body, two opposite discharge grooves formed on opposite sides of said drill body, and two cutting edges each formed at a place where said drill body meets each of said opposite discharge grooves; a plurality of thread convolutions spirally disposed around said shank; a drilling portion formed at a distal end of said drill body opposite to said head and terminating at a first tip, with a first horizontal line passing said first tip, said central axis of said shank passing through said first tip, two blade portions being formed on said drill body and located opposite to each other so that said drilling portion is located between said two blade portions; and said drill body defining two curved lines at two sides of said first tip; wherein each of said two blade portions extends from each of said two cutting edges and tapers to form a second tip having a second included angle defined between 30 degrees and 50 degrees, with a second horizontal line passing said second tip, two opposite concave surfaces being recessedly formed on said opposite sides of said drill body to define said two curved lines, each of said two curved lines being formed at an edge where each of said two concave surfaces meets each of said two discharge grooves and formed by extending from said first tip to each said second tip, with a point of each said curved line furthest from said first horizontal line being above said second horizontal line to facilitate a sharp cutting operation executed by said two blade portions, wherein said first tip of said drilling portion has a first included angle defined between 30 degrees and 60 degrees, with said first included angle being larger than said second included angle, a distance between said first tip and said head being larger than a distance between each said second tip and said head. a head having a bottom surface; a shank extending longitudinally from said bottom surface of said head and defining a central axis, wherein said shank forms a leading section located opposite to said head, said leading section including a drill body, two opposite discharge grooves formed on opposite sides of said drill body, and two cutting edges each formed at a place where said drill body meets each of said opposite discharge grooves; a plurality of thread convolutions spirally disposed around said shank; a drilling portion formed at a distal end of said drill body opposite to said head and terminating at a first tip, with a first horizontal line passing said first tip, said central axis of said shank passing through said first tip, two blade portions being formed on said drill body and located opposite to each other so that said drilling portion is located between said two blade portions; and said drill body defining two curved lines at two sides of said first tip; wherein each of said two blade portions extends from each of said two cutting edges and tapers to form a second tip having a second included angle defined between 30 degrees and 50 degrees, with a second horizontal line passing said second tip, two opposite concave surfaces being recessedly formed on said opposite sides of said drill body to define said two curved lines, each of said two curved lines being formed at an edge where each of said two concave surfaces meets each of said two discharge grooves and formed by extending from said first tip to each said second tip, with a point of each said curved line furthest from said first horizontal line being above said second horizontal line to facilitate a sharp cutting operation executed by said two blade portions, wherein said first tip of said drilling portion has a first included angle defined between 30 degrees and 60 degrees, with said first included angle being larger than said second included angle, a distance between said first tip and said head being larger than a distance between each said second tip and said head.