One major parameter of the wireless communication systems that allows the sender and the receiver to communicate is the transmission power. For most of wireless communication module, the transmission power is configurable by applying a special command. This method is a persistent configuration but in wireless sensor network applications, the sensor nodes are installed in various distances and environments, which require a different transmission power. The transmission power adjustment affects the overall performance. The exorbitant configured transmission power increases the power consumption of the sensor node. On the other hand, the communication performance will be decreased when the configured transmission power is too low. This paper proposes the automatic transmission power adjustment method. The client’s transmission power will be adjusted once it receives the adjusting command from the base station in order to optimize the power consumption and communication performance according to experimental distance.