The invention relates to a powder conveying system for a portable laser repairing device and belongs to the technical field of powder conveying in the laser repairing process of surface cracks on metal pieces. The powder conveying system comprises four parts: a speed-governing air pump, a powder feeder, a photoelectric detection sensor and a coaxial powder-feeding nozzle, which are successively connected through a horizontally arranged cylindrical pipeline; a pneumatic conveying mode is adopted by the system; a controllable airflow is generated by an air source, is fed into a main conveying pipeline through an airflow guide pipe, forms a Venturi structure at an outlet of the powder feeder and drives the powder outputted by the powder feeder to flow and form gaseous and solid two-phase fluids; the powder is conveyed to a processing area by the coaxial powder-feeding nozzle; the photoelectric detection sensor is placed on the main conveying pipeline; the revolving speed of the screw shaft and the powder-feeding volume can be adjusted according to the practical working conditions and measured value. The powder conveying system for the portable laser repairing device is capable of realizing the stable controllability of powder conveying; the output fluid has a better converging state; the system has a small volume and a compact structure, is capable of avoiding the limitation of processing condition and position and is especially suitable for the powder-moving supply occasion under the conditions of small powder quantity and multi-station.