In order to select the suitable modulation parameters for harmonic signal and meet the different measurement requirements,taking a oxygen monitoring system with 760.77 nm absorption wavelength for example,the impact of different amplitude values on the symmetry,both sides minimum interval and signal integrity were discussed by changing the sawtooth and sine signal frequency.The result show that the Sinmulink values are highly relevant with experiment values and a good second harmonic signal is obtained when the ratio fsin/fsaw is 1 000.The results have profound guiding significance for the system precision,stability,repeatability and other important aspects of the experimental system.