Abstract: Ever since wireless sensor networks (WSNs) have emerged, different optimization techniques have been proposed to overcome their constraints like energy efficiency, delay, finding the best route, etc. Furthermore, the proposal of new applications for WSNs has also created new challenges to be addressed. The concept of Cross-layer gave a verity of optimization techniques to the world of sensor networks and the approaches have proven to be the most efficient optimization techniques for these problems, since they are able to take the behavior of the protocols at each layer into consideration. Thus, this survey proposes to identify the key problems of WSNs and gather available crosslayer solutions for them that have been proposed so far, in order to provide insights on the identification of open issues and provide guidelines for future proposals. In this paper, the need for cross layer design in WSN and the interaction between the layers is discussed first and later we discussed the different types of cross layer techniques