Variety in customers’ demands, increasing competition, rapidly changing technologies and shortening time to market describes driving forces for product development process. Manufacturing companies respond with different approaches on those driving forces. One of the approaches is to offer a wider range of product assortments. If the potential of component commonality is neglected, the explosion of product assortments leads to high costs in design, production, assembly etc. Therefore, companies need to design a wider range of product assortments with the less variations in design by increasing the reuse of components. With that approach companies are focusing to the development of product family. Conducted theoretical and practical research has resulted in definition of the criteria and process of identification and analysis of common components in group of products. The process begins with the analysis of internal and external variety among the group of products. External variety is defined from the existing group of products and it represents the necessary functional variety seen from the customers’, i.e. market, viewpoint. The required internal variety is defined based on the external variety, so that it represents the necessary variety seen from the company’s viewpoint. To analyse a group of products the function-assembly decomposition structure was established. For the functions at the lowest levels of each branch in the functionassembly decomposition structure the value of commonality index was calculated using the method “Total Constant Commonality Index”. Based on the calculated data the functions are classified as the functions with the lower and higher values of commonality index. The identification of components which have a stronger influence on the reduction of the commonality value has to be applied to the set of functions with the lower value of commonality index. Identification of components is applied using the method Component Part Commonality Index. Identified components have to be further analyzed and redesigned. The result of redesign process is a new version of component which will replace existing components. The identification of components which are more often reused in the group of products has to be applied to the set of functions with the higher value of commonality index. Those components have to be kept or partially redesigned in order to achieve higher reuse of components. The defined criteria and process of identification and analysis of common components in group of products are applied and detailed described on the industrial example of current transformer of company KONČAR – Instrument transformers, Inc.