An inner brace type non-backlash spline comprises a spline shaft (1), an intermediate shaft (2), a pin (3) and a nut (4). The pin (3) penetrates a pin runner (5) and is inserted into a pin hole on theintermediate shaft (2). The nut (4) is equipped to the screw of the spline shaft (1). The intermediate shaft (2) is inserted into an inner hole of the spline shaft (1) from an outer spline spring leaf chuck of the spline shaft (2) and struts the outer spline spring leaf chuck through a trumpet member at the end of the intermediate shaft (2). An outer spline (6) at one end of the spline shaft (1)and one part of the adjacent elastic sheet (7) are uniformly divided into four sections. Furthermore the spring leaf chuck of the outer spline extends into the inner part of the workpiece. The other end of the spline shaft (1) is fixedly connected with a shaft coupling. The pin (3) and the intermediate shaft (2) are moved along the runner through screwing the nut (4) so that the matching precisionbetween the inner brace type non-backlash spline and the components obtains a preset requirement and the positioning precision is increased. The inner brace type non-backlash spline furthermore has the characteristics of simple structure and convenient use.