A flow control method of a hydraulic pump for a construction machine including a variable displacement hydraulic pump, at least one hydraulic actuator connected to the hydraulic pump, a spool controlling hydraulic fluid supplied to the hydraulic actuator when shifted by signal pressure that is supplied in proportion to an operation rate of an operation lever, a first sensor detecting discharge pressure of the hydraulic pump, a second sensor detecting signal pressure according to the operation rate of the operation lever for each of the hydraulic actuators, and a control unit controlling a discharge flow rate of the hydraulic pump in accordance with detection signals of the first and second sensors (7, 8), the flow control method comprises: a first step of detecting the discharge pressure of the hydraulic pump by the first sensor and the operation rate of the operation lever for each of the hydraulic actuators by the second sensor; a second step of setting standard load pressures of each of the hydraulic actuators, respectively; a third step of comparing levels of the discharge pressure of the hydraulic pump and the standard load pressures of each of the hydraulic actuators, where each operation rate is detected by the second sensor; a fourth step of adjusting coefficients of a relationship between the operation rate and the discharge flow rate of the hydraulic pump, so that a discharge flow rate of the hydraulic pump is proportionally reduced in proportion to the operation rate in accordance with degrees of loads generated by the hydraulic actuators if the discharge pressure of the hydraulic pump is higher than the standard load pressures of each hydraulic actuator; and a fifth step of controlling the discharge flow rate of the hydraulic pump in proportion to the operation rate if the discharge pressure of the hydraulic pump is not higher than the standard load pressures of each hydraulic actuator; characterized in that, even in the case where the coefficients of the relationship are changed in accordance with the degrees of load generated by the hydraulic actuators and the discharge flow rate of the hydraulic pump for the operation rate is reduced, a variation range of the coefficients is limited so that the maximum flow rate of the hydraulic pump can be discharged for the operation rate that is higher than a predetermined value. a first step of detecting the discharge pressure of the hydraulic pump by the first sensor and the operation rate of the operation lever for each of the hydraulic actuators by the second sensor; a second step of setting standard load pressures of each of the hydraulic actuators, respectively; a third step of comparing levels of the discharge pressure of the hydraulic pump and the standard load pressures of each of the hydraulic actuators, where each operation rate is detected by the second sensor; a fourth step of adjusting coefficients of a relationship between the operation rate and the discharge flow rate of the hydraulic pump, so that a discharge flow rate of the hydraulic pump is proportionally reduced in proportion to the operation rate in accordance with degrees of loads generated by the hydraulic actuators if the discharge pressure of the hydraulic pump is higher than the standard load pressures of each hydraulic actuator; and a fifth step of controlling the discharge flow rate of the hydraulic pump in proportion to the operation rate if the discharge pressure of the hydraulic pump is not higher than the standard load pressures of each hydraulic actuator; characterized in that, even in the case where the coefficients of the relationship are changed in accordance with the degrees of load generated by the hydraulic actuators and the discharge flow rate of the hydraulic pump for the operation rate is reduced, a variation range of the coefficients is limited so that the maximum flow rate of the hydraulic pump can be discharged for the operation rate that is higher than a predetermined value.