In this paper, the authors review different mobile agent based data gathering system in wireless sensor network that are proposed by different researchers. The major concern in wireless sensor network is of improving the lifetime of the network, decreasing the execution time and energy consumption. So the overall goal is to collect the data efficiently. Two major factors affecting this concern are communication and processing. Both of these issues are successfully addressed by the use of mobile agents. Different researches have proposed their theories for efficiently collecting the data by using mobile agents and the result of the simulation show that their proposed approach has improved performance gain.