This paper presents an electrical power source with arbitrary harmonics generating for power quality measurement devices in calibration. Harmonics generating theory illustrate the design challenge should be generating groups of accurate sinusoidal signals with different amplitudes, frequencies and initial phases simultaneously. We discuss various approaches for digital sinusoid generating, and decide to use the CORDIC algorithm implemented on an FPGA. The hardware implementation including the block diagram and the system structure is given. It is demonstrated that the number of points per circle barely affect the accuracy when it is more than 2000. A fundamental with distortion on all harmonics up to the 50th order is generated. The experimental results show the amplitude accuracy and phase accuracy of all the channels achieve the design target. We also give and discuss the longtime drift of voltage and power accuracy.