The invention relates to a coaxial powder feeding system aiming at heterogeneous materials. According to the system, through the interaction of a powder compounding device and a powder feeding device,a control part pre-calculates a powder feeding rate required for a single scanning path, a time interval between a front path and a back path, and fast on-off of a rapid powder switch between different powder feeding paths for two times, and timely treats residual powder, so that continuous cladding processing of functionally graded materials is realized, components are formed at one time, and aproduct is ensured to be stable in mechanical performance and high in processing accuracy. According to a powder compounding program of the control part, the rotating speed of multiple groups of stepping motors in the powder compounding device is adjusted in real time, and multiple powder is mixed according to the specified proportion and is stored in a powder collecting bin, so that conditions are provided for the accurate and fast switchover of powder proportions between different scanning paths.