Wireless sensor network are event-driven network systems consist of collection of sensor nodes that are deployed to monitor physical and environmental conditions. In Wireless sensor network, whenever an event is detected, then the data related to the event need to be sent to the sink node (data collection node). While forwarding the data from the source node to sink node there may be chance for congestion due to heavy data traffic. Due to congestion, it leads to data loss, it may be important data also. Objective of this paper is to review various existing methods to detect and control the congestion. Different parameters that are used to measure the congestion also reviewed. Finally a comparison of various parameter measures was presented.