It provides a theoretical basis for judging the uniformity of the powd er raw materials of the sintered tumble polishing abrasive block in the finishin g technology,and proposes a powder image similarity detection theory.Firstly, the sampling wheel is used to collect the powder samples,and the powder images are collected through the digital microscope.The collected powder images are gr ayed out,sampled down,filtered and sharpened to filter out the noise during th e collection process and make the details of the images clearer.Secondly,the fe ature parameters based on gray histogram are extracted,and the feature paramete rs and weight of the central image are obtained by means of mean value method.Fi nally,the weighted Euclidean distance between each image and the center image i s calculated,and the gray distribution similarity of the image is represented b y the distance mean value.The experimental results show that the variation trend of gray distribution similarity of powder images with time is obtained through simulation analysis of powder images collected at different times in the process of powder mixing,which provides a basis for the judgment of powder mixing unif ormity in later work.