Up till now, less research has been done in developing a Wireless Sensor Network (WSN) data aggregation with the help of Object OrientedModeling and Design (OOMD). These kinds of applicationincludeuse of complex data structures and different algorithms for aggregating data. Usually for such calculation, mathematical modeling is done. To visually represent any research problems,Unified Modeling Language (UML)is more efficient tool for modeling. In this paper, demonstration of UML diagrams is presented for modeling of data aggregation in WSN which leads to better development of application. As a result of additional sensor nodes being deployed in the wireless sensor networks, demand on resource constraints is reduced, whichleads to increase in redundantdata. Data aggregation protocol helps to reduce this redundancy by organizing the data efficiently. Due to the constraints on energy in the WSNs, Use of data aggregation techniques and data dissemination across WSN plays an significant role in the network life cycle time as they help to conserve the energy of sensor nodes. In this, data is collected by sensor node, then dedicated cluster node aggregates it with data aggregation algorithm and then it is forwarded to base station. This flow of various activities is modeled using UML diagrams. Heresystem is analyzed withhelp of use case diagram, class diagram, sequencediagram, collaborationdiagram and activity diagram. Modeling this kind of problems using UML approach helps to visualize, specify,construct and document the system artifact effectively which is helpful for various stakeholders of the application.