As the end of life becoming more and more complex recycling systems encountered many difficulties in valuing all the materials contain in each product. This involves not only recovering a large number of materials but also doing so with the minimal environmental impact. Although the benefits of recycling are well established, the industrial processes need to be designed in regard with their environmental impacts. That why recyclers need robust assessment tools to make the right choices during the design of recycling processes. This evaluation work should enable them to choose the right recycling solutions for a wide range of end of life products. In this article, we present how we develop a methodology for evaluating the performance of recycling processes during their design phase. This methodology is our answer to help optimise the recycling of multi materials products based on the evaluation of the sustainability performance of the processes chosen.