A bicycle shifting structure being fixed on a handlebar of a bicycle to control a bicycle device and comprising: a clamping assembly including a first retainer, a second retainer corresponding to the first retainer, two hollow engaging portions defined on the first retainer and the second retainer and used to engage the handlebar, and a positioning bolt for screwing the first retainer and the second retainer together; a rotary shift set including a rotating seat and a rotation member pivoted on a first end of the rotating seat and rotated by a rider to rotate on the rotating seat; characterised in that a height adjusting assembly fixed between the clamping assembly and the rotary shift set and including two retaining portions, each having a central axis line for matching with a central axis line of each engaging portion so that an angle θ is defined between the central axis line of each retaining portion and the central axis line of each engaging portion; wherein the rotating seat has an abutting post one piece formed on a second end thereof and retained and moving in the two retaining portions of the height adjusting assembly, and by unscrewing and screwing the positioning bolt, the height adjusting assembly is moved and fixed; a tightness adjusting set mounted on the height adjusting assembly and including a screwing element inserted into and screwed with the abutting post, a rotatable button fitted on the screwing element and fixed on an end portion of the abutting post, a fitting member and a steel rope which are inserted into the screwing element and the abutting post and are positioned on the rotation member, a first end of the steel rope connecting with the bicycle device, wherein the rotation member pulls the steel rope when the rotating seat rotates so that the screwing element and the rotatable button rotate simultaneously to change a distance between the abutting post and the screwing element, hence a length of a part of the steel rope outside the fitting member is adjusted to pull the steel rope tightly or loosely. a clamping assembly including a first retainer, a second retainer corresponding to the first retainer, two hollow engaging portions defined on the first retainer and the second retainer and used to engage the handlebar, and a positioning bolt for screwing the first retainer and the second retainer together; a rotary shift set including a rotating seat and a rotation member pivoted on a first end of the rotating seat and rotated by a rider to rotate on the rotating seat; characterised in that a height adjusting assembly fixed between the clamping assembly and the rotary shift set and including two retaining portions, each having a central axis line for matching with a central axis line of each engaging portion so that an angle θ is defined between the central axis line of each retaining portion and the central axis line of each engaging portion; wherein the rotating seat has an abutting post one piece formed on a second end thereof and retained and moving in the two retaining portions of the height adjusting assembly, and by unscrewing and screwing the positioning bolt, the height adjusting assembly is moved and fixed; a tightness adjusting set mounted on the height adjusting assembly and including a screwing element inserted into and screwed with the abutting post, a rotatable button fitted on the screwing element and fixed on an end portion of the abutting post, a fitting member and a steel rope which are inserted into the screwing element and the abutting post and are positioned on the rotation member, a first end of the steel rope connecting with the bicycle device, wherein the rotation member pulls the steel rope when the rotating seat rotates so that the screwing element and the rotatable button rotate simultaneously to change a distance between the abutting post and the screwing element, hence a length of a part of the steel rope outside the fitting member is adjusted to pull the steel rope tightly or loosely.