Disclosed is a hydraulic pump control system for minimizing flow loss by optimally limiting the discharge flow volume of the hydraulic pump when an upper swivel body is made to swivel abruptly. The hydraulic pump control system according to the present invention comprises: a swivel motor which is connected to a hydraulic pump; a control spool for the swivel motor, which controls the hydraulic fluid supplied to the swivel motor during switch back by means of a control signal for a remote control valve; an orifice which is provided on the furthest downstream side of a center bypass pathway; a regulator which controls the angle of inclination of the swash plate of the hydraulic pump; a swivel operation signal detection means which detects a swivel operation signal output from the remote control valve; an electronic proportional pressure reducing valve which outputs a secondary pressure proportional to the detection signal of the swivel operation signal detection means; and a shuttle valve of which the input sides are respectively coupled to the orifice and the electronic proportional pressure reducing valve, and the output side is coupled to the regulator.