Aiming at the problem of tracking and searching people in crowded areas,a portable tracker based on WiFi probe is designed.Firstly,two ESP8266 chips are selected for hardware circuit design.Secondly,the author can capture the 802.11 probe packet sent by the mobile phone by coding the ESP8266 chip software,and can perform WiFi network transmission.Thirdly,the author can obtain the MAC address and signal strength of the mobile phone after analyzing the probe packet.Finally,the author converts the collected probe data RSSI into distance,so that the location of the target user can be obtained in real time,and the tracker can determine whether there is a target person within a certain range.In addition,the tracker is equipped with communication modules such as Bluetooth,WiFi,GPRS,etc.,which can send the detected data to the user's mobile phone or a remote server.The WiFi probe tracker has low hardware cost and is easy to use,and can be better applied to the application field of personnel tracking and traceability.