Recently, considerable attention has been focused on the investigation of the use of wireless sensor networks (WSN) to drive autonomous mobile robot for navigation in flexible, indoor environments instead of fixed locations, for their potential as a cheap, easily deployed, and distributed monitoring tool. However, such composite net systems are nontrivial to design for the robot systems typically assume the map known in advance, or they need to build the map while moving around, with the help of acquired sensor network infrastructure information. The key component for determining the robot's pose by the information of physical location of the sensor nodes after they have been deployed is known as the problem of localization. In this paper we propose an environment map free navigation algorithm based on RF wireless sensor networks for an indoor autonomous mobile robot. In our navigation system, the robot can navigate autonomously without the need for a map, by acquiring the information of pre-set radio emission sensors deployed in an indoor environment. By measuring the distance from one sensor node after another using triangular localization method, the robot locates itself and knows its pose. The proposed algorithm is conceptually simple and easy to implement. Our approach is applied to a mobile robot platform, simulation and experimental results show that good localization can be achieved using the proposed method.