Multiple-stage power-shift transmission of planetary design for a vehicle for being arranged between a drive shaft and an output shaft, the multiple-stage transmission having two parallel shaft trains (WS1, WS2), six selector elements (K1, K2, K3, K4, B1, B2), at least two spur gear stages (STS1, STS2) and three planetary gear sets (PS1, PS2, PS3), the planetary gear sets (PS1, PS2, PS3) in each case having a sun gear (SO1, SO2, S03), an internal gear (HO1, H02, H03) and a planetary carrier which is combined in a spider (ST1, ST2, ST3) and has a plurality of planetary gears, it being possible for the two shaft trains (WS1, WS2) to be connected to one another via the at least two spur gear stages (STS1, STS2), it being possible for various transmission ratios between the drive shaft and the output shaft to be brought about by way of selective engagement of the six selector elements (K1, K2, K3, K4, B1, B2), with the result that a plurality of forward gears, in particular nine forward gears, and at least one reverse gear can be realized; characterized in that the three planetary gear sets (PS1, PS2, PS3) and the drive shaft are arranged on a first shaft train of the two parallel shaft trains (WS1, WS2), the output shaft is arranged on a second shaft train of the two parallel shaft trains (WS1, WS2), a sun gear of a second planetary gear set of the three planetary gear sets (PS1, PS2, PS3) and the drive shaft are connected to one another in a torsionally fixed manner and form a first connecting element, a sun gear of a first planetary gear set of the three planetary gear sets (PS1, PS2, PS3) and a spider of the second planetary gear set are connected to one another and form a second connecting element, an internal gear of third planetary gear set of the three planetary gear sets (PS1, PS2, PS3) and the spider of the second planetary gear set are connected to one another in a torsionally fixed manner and form a third connecting element, an internal gear of the second planetary gear set and a first spur gear (ST2a) of a second spur gear stage of the at least two spur gear stages (STS1, STS2) are connected to one another and form a fourth connecting element, a first spur gear (ST1a) of a first spur gear stage of the at least two spur gear stages (STS1, STS2) and an internal gear of the first planetary gear set are connected to one another and form a fifth connecting element, a second spur gear (ST1b) of the first spur gear stage and the output shaft are connected and form a sixth connecting element, a spider of the first planetary gear set and the drive shaft are connected to one another and form a seventh connecting element, a second spur gear (ST2b) of the second spur gear stage and the output shaft are connected to one another and form an eighth connecting element, a second selector element of the six selector elements (K1, K2, K3, K4, B1, B2) being arranged in the force flow between the drive shaft and a spider of the third planetary gear set, a third selector element of the six selector elements (K1, K2, K3, K4, B1, B2) being arranged in the force flow between the fourth connecting element and the spider of the third planetary gear set, a fifth selector element of the six selector elements (K1, K2, K3, K4, B1, B2) being arranged in the force flow between the spider of the third planetary gear set and a transmission housing, and a sixth selector element of the six selector elements (K1, K2, K3, K4, B1, B2) being arranged in the force flow between a sun gear of the third planetary gear set and the transmission housing.