1. A computer-readable storage medium which stores non-transitory instructions which, when executed by a computer, perform a program-converting method for multi-axis coordinated machines and are applied to a program-converting device having a first input circuit, a second input circuit, a setting circuit and a conversion circuit, the program-converting method comprising: inputting machining programs and mechanism data of a plurality of first machines to the first input circuit; inputting mechanism data of a plurality of second machines to the second input circuit, the second machines each having a second configuration different from a first configuration of each of the first machines; setting at least one of the first machines to be a source machine and setting one of the second machines to be a target machine by the setting circuit; and using a kinematical method by the conversion circuit to convert a machining program of the source machine into a machining program applicable to the target machine based on the mechanism data of the source machine and the target machine.