The unique characteristics of WSN such as coherent nature of traffic to base station that occurs through its many-to-one topology and collision in physical channel are main reasons of congestion in wireless sensor networks. Also when sensor nodes inject sensory data into network the congestion is possible. Congestion affects the continuous flow of data, loss of information, delay in the arrival of data to the destination and unwanted consumption of significant amount of the very limited amount of energy in the nodes. Therefore Congestion in wireless sensor networks (WSN) needs to be controlled in order to prolong system lifetime improve fairness, high energy-efficiency, and improve quality of service (QoS). This paper has mainly described the characteristic and the content of congestion control in wireless sensor network and surveys the research related to the Congestion control protocols for WSNs.