The image features of copper flotation froth image means the size of the area of local black hydration in the froth image, which is called local spectral feature and related to flotation performance. A local spectral feature extraction method based on MPCA was proposed for the irregularity of the size and the shape, and the extracted features were used in copper rougher flotation process to identify sick conditions. Firstly, we described the copper rougher flotation process and analyzed the impact of the main factors roughing process and the formation mechanism of black hydration region. Then, a method was proposed to extract the local feature of image based on MPCA. Lastly, the image local feature extraction algorithm based on MPCA was applied to the copper flotation rougher froth image and the extracted image features were used in copper rougher process for sick condition recognition. The validity of the proposed method has been verified with industrial data.