Laser cladding monitoring is one of the cladding layer quality controlling methods. In this paper, one of the characteristic signal of plasma optical signal has been detected by phototube. TEM00 laser has been used in experiments with two scans like powder present cladding. Powder use Ni60 and the base material is 45# steel. The relationship between blue-violet light intensity and laser power scan velocity, as well as the relevance between quality of layer and intensity have been discussed. The results indicate that while laser power grows, the intensity increases just at a low rate, and the intensity decreases as scan velocity increases when the power is lower than a definite value. But when the power is greater than the values, the intensity will rise as velocity increases. The quality of layer is improved greatly when the intensity value rangs from 1.7 to 2.5 μW/cm2 with a slight fluctuation. Analysis shows that when the laser power threshold is breaken, the scanning speed increases and penetration shallows, and energy for material vaporizing increases, so intensity of blue-violet light grows.