A target transaction initiated by a member node device in a blockchain is received, where the target transaction include a reference time parameter, and where the reference time parameter is used to determine whether the target transaction is a valid transaction within a transaction validity period. Based on the reference time parameter, a determination is performed as to whether the target transaction is a valid transaction within a transaction validity period. In response to determining that the target transaction is a valid transaction within the transaction validity period, the target transaction is recorded to a generated candidate block.