In order to improve the practicability and security of quantum key distribution (QKD) technology, it is an important research direction in the field to explore the possible security vulnerabilities in QKD system and study the corresponding defense strategies. Dead time attack is a kind of attack against QKD system with multi-channel detectors, in which the attacker uses the death time effect of single-photon avalanche photodiode to blind the designated channel to destroy the security of the key generated by QKD system. Aiming at this type of attack, a new anti-dead time attack scheme based on time measurement technology to dynamically setting dead time length is proposed. The proposed scheme uses TDC time measurement technology to ensure that the multi-channel detectors can enter and exit the dead time state simultaneously to achieve the defense goal. The feasibility of the scheme is verified on the test platform.