A drilling tool comprising: a cutting insert , wherein the cutting insert has a cutting edge at a front end portion ; a main body , wherein the main body is mounted with the cutting insert ; a hollow discharge channel , wherein the hollow discharge channel is formed inside the main body , and the hollow discharge channel has a curved surface for guiding a chip (S) in a direction towards a base end portion opposite to the front end portion , wherein the hollow discharge channel is formed between a rotation axis of the drilling tool and the outer circumferential surface , wherein the curved surface is an inclined surface configured to apply an urging force on the chip (S) in a direction towards the base end portion during rotation of the drilling tool, wherein the drilling tool is provided with a plurality of cutting inserts , and a plurality of discharge channels being formed to extend from the front end portion to the base end portion , and the number of the discharge channels are same as the number of the cutting insert , wherein the plurality of discharge channels are axisymmetrical about the rotation axis of the drilling tool as a center, wherein the drilling tool further comprises a supporting member , the supporting member is mounted on the base end portion of the main body and supports the main body , and is provided with a hollow flow channel in communication with the discharge channel of the main body , wherein the drilling tool further comprises a cutting oil feed passage for feeding cutting oil; the drilling tool is characterised in that : the curved surface is formed with a helical shape around the rotation axis of the drilling tool, and in that the discharge channels are connecting with each other during extending. a cutting insert , wherein the cutting insert has a cutting edge at a front end portion ; a main body , wherein the main body is mounted with the cutting insert ; a hollow discharge channel , wherein the hollow discharge channel is formed inside the main body , and the hollow discharge channel has a curved surface for guiding a chip (S) in a direction towards a base end portion opposite to the front end portion , the hollow discharge channel is formed inside the main body , and the hollow discharge channel has a curved surface for guiding a chip (S) in a direction towards a base end portion opposite to the front end portion , wherein the hollow discharge channel is formed between a rotation axis of the drilling tool and the outer circumferential surface , wherein the curved surface is an inclined surface configured to apply an urging force on the chip (S) in a direction towards the base end portion during rotation of the drilling tool, wherein the drilling tool is provided with a plurality of cutting inserts , and a plurality of discharge channels being formed to extend from the front end portion to the base end portion , and the number of the discharge channels are same as the number of the cutting insert , wherein the plurality of discharge channels are axisymmetrical about the rotation axis of the drilling tool as a center, wherein the drilling tool further comprises a supporting member , the supporting member is mounted on the base end portion of the main body and supports the main body , and is provided with a hollow flow channel in communication with the discharge channel of the main body , wherein the drilling tool further comprises a cutting oil feed passage for feeding cutting oil; the drilling tool is characterised in that : the curved surface is formed with a helical shape around the rotation axis of the drilling tool, and in that the discharge channels are connecting with each other during extending. the curved surface is formed with a helical shape around the rotation axis of the drilling tool, and in that the discharge channels are connecting with each other during extending. <EOS>