The present invention discloses a bridge imbalance PUF unit circuit and multi PUF circuits; the bridge imbalance PUF unit circuit comprises a four-arm bridge unit circuit and a contrast output unit circuit; the multi PUF circuits comprise a timing controller, a row decoder, a column decoder, a memory array, a row output circuit and a column output circuit; each memory unit in the memory array comprises a bridge imbalance PUF unit circuit and 4 NMOS tubes; the present invention features in higher randomness that is up to 51.8% at the supply voltage of 1.2V under the temperature of 25° C.