Abstract: As a new indoor positioning technology, the RSSI (Receive Signal Strength Indicator) value acquired from wireless router is widely used in the field of indoor mobile robot localization. In order to achieve the indoor mobile robot positioning, the probability positioning method is proposed based on the RSSI value. The characteristics of the RSSI distribution in the indoor environment are discussed, together with the principle of probability positioning. The positioning system of the indoor mobile robot based on VC++ 6.0 platform was developed. It includes two parts, the hardware platform and the software platform. The mobile robot localization experiment was carried out in the indoor environment. It is shown that the positioning accuracy is affected by some factors, the obstacles, the human body, temperature and humidity, etc. The maximum deviation is 1.2758m and the minimum is 0.3007m. The positioning requirements for the indoor mobile robot localization can be met.