Anti-theft system and operating method thereof

An anti-theft system, comprising:

• a wearable device comprising a first wireless module, a first processing module and a first positioning module;
• and
• a portable electronic device comprising a second wireless module, a second processing module and a second positioning module, wherein the first wireless module and the second wireless module are in a wireless connection with each other, and the second wireless module detects a received signal strength indicator value of the wireless connection,
• wherein if the received signal strength indicator value is lower than a predetermined signal strength value, the first positioning module and the second positioning module are enabled to respectively generate plural wearable device position data and plural portable electronic device position data within a predetermined time period, and the second processing module calculates a displacement of the portable electronic device according to the plural wearable device position data and the plural portable electronic device position data and determines whether a warning mode is enabled according to the displacement.