The present disclosure belongs to an identity authentication technology in network security field, and relates to a lightweight identity authentication method. The method utilizes lightweight operations of the physical unclonable function, Hash operation, XOR operation, etc. for bidirectional authentication between an authentication server and an Internet of Things resource-limited device, and particularly utilizes uniqueness of an integrated circuit (IC) physical microstructure created by the physical unclonable function in the resource-limited device in a manufacturing process to design an engineering-implementable information desynchronization recovery mechanism of two authentication parties by optimizing an interaction mode of input challenge and output response of the physical unclonable function, thereby solving the problem that the same lightweight identity authentication type solution cannot ensure forward security and resist desynchronization attack, further reducing resource cost for an identity authentication process, and effectively improving security and operation efficiency of identity authentication of the Internet of Things resource-limited device.