The invention discloses an RFID (Radio Frequency Identification Device) tag chip true random number generator which has high university, and less power consumption and a smaller area, can be tested through various random number properties, and comprises a high-frequency ring-shaped oscillator, a sampler, a controller, a counter, a seed register and an element cellular automata, wherein the high-frequency ring-shaped oscillator can generate a high-frequency signal under the control of the controller, the high-frequency signal output by the high-frequency ring-shaped oscillator is sampled by the sampler to obtain a seed value, under the control of the counter, the seed value is stored in the seed register, the seed register is connected with the element cellular automata, and a true random number is obtained after the processing of the element cellular automata. The seed register is a 32-position register, the element cellular automata is a 37-level cellular automata displacement register, the counter is a counter with 32 bit, and the high-frequency ring-shaped oscillator is a high-frequency ring-shaped oscillator with RC (Remote Control) delay.