In wireless fading channels, the path-loss exponent (PLE) is one of the most fundamental parameters to characterize the channel propagation. It has an important impact on the received signal strength (RSS)-based localization in wireless sensor networks (WSN). On the other hand, the communication range of a sensor in a WSN depends on the transmission power and on the environment (outdoor or indoor). Hence, the propagation conditions have a great influence on the connectivity between sensors in WSN, especially in complex environments. Nevertheless, most approaches used to estimate the PLE require some information of the wireless network such as RSS at some nodes, or some external information such as Global Positioning System. However, this information might be sometimes unreliable or difficult to obtain. In this paper, we propose a method to estimate the PLE based on the connectivity between sensors deployed in a determined area.