The invention provides a low-power-consumption real-time noise-reduction and sharpening merged preprocessing algorithm for a CMOS image sensor. The low-power-consumption real-time noise-reduction and sharpening merged preprocessing algorithm aims to solve the problems that in the prior art, according to a CMOS image sensor image preprocessing method, a denoising algorithm and a sharpening algorithm are executed separately, the algorithm is high in complexity, and saving hardware resources and reducing the total power consumption are not facilitated. By means of the low-power-consumption real-time noise-reduction and sharpening merged preprocessing algorithm, input light signals are divided into three primary colors of red, green and blue (RGB), namely three kinds of pixels RGB through a color filter array (CFA), data cache is conducted in the mode that data are stored in a on-chip blocked and classified mode, the noise of the pixels RGB is reduced through a space self-adaptive noise reduction algorithm, an laplace operator and a smoothness operator are combined to generate a new operator model, and sharpening processing is conducted on the G pixel through the new operator model. The low-power-consumption real-time noise-reduction and sharpening merged preprocessing algorithm has the advantages that noise reduction and sharpening are merged together, complexity is lowered greatly, hardware overhead and total power consumption are reduced greatly, the hardware design difficulty is lowered, the processing speed is increased, performance is better, and the algorithm is easy to implement.