Abstract: Miner’s lamp has potential risk in normal operations due to the limitation of miner’s lamp protector in current protection.Based on the theory of intrinsic safety of the power circuit,by analyzing the impact of cascade current limiter on the performance of the LED light source in miner’s lamp circuit,the paper selects the type of limited current,designs and studies the structural principle of current-limiting protective parts,optimizes and decides the operating parameters of limited current circuit,and develops an applicative,efficient,reliable and ideal limited current circuit.The protection class of this limited current circuit can reach "ia".