SCM control technology be applied to inductively coupled plasma excitation source in this paper. Through controlling thyristor trigger angle control AC voltage regulation, the go through step-up circuit to achieve output power continuously adjustable. It introduces construction and work principle. Grating spectrograph is co-operated with thyristor AC voltage ICP excitation source for performance tested. By means of Ar355.431nm tested power stability≤0.5%. Testing Fe, Cu, Au and other elements shows that the detection limit is 10-9g/ml, precision relative standard deviation RSD≤ 3％. Results show that this voltage regulation technology is stable, reduces the instrument’s size and operates conveniently. It is suitable for ICP excitation source in spectroscopic analysis.