With the development of society and the progress of science and technology, consumers prefer to choose personalized products. Therefore, multiple-variety and small-batch production mode becomes the mainstream of manufacturing. However, under the multiple-variety and small-batch production mode, it is difficult for companies to control quality and analyse process capability because of the lack of process data. To solve this problem, processes which were similar to target process were sorted out using the principle of similarity cell based on factors which influenced the processes, and then the target process and the similar processes were made into one group. After data from different processes was transformed to the standard, the sample space of target process was expanded. Then quality control and analysis of process capability were carried out on target process using the expanded process data. At last, a turning process in a workshop was taken as an example, its process capability index was obtained by using the proposed method. The result showed that the capability of target process was satisfactory, and the result agreed with the reality. The results show that much convenience can be brought to enterprises to control quality and analysis process capability under the multiple-variety and small-batch production mode.