In process of real time acquisition and transmission, the spectral signal obtained by miniature spectrometer may contain noise signals superposed on it. But the traditional denoising methods can't achieve the expected performance because of their limitations. A de-noising method for spectral signal in miniature spectrometer based on Stationary Wavelet Transform (SWT) is proposed. We compared the performance of our de-nosing method with that of the traditional method. Simulation and experimental results prove that using sym5 basis, decomposition at level 5, soft shrinkage function with heuristic SURE threshold rule achieved superior performance in miniature spectrometer spectral signal denoising.