Pain diagnosis and management benefit the development of objective assessment of nociception during general anesthesia. In the past decades, research addressing this issue has focused on monitoring changes in the autonomic nervous system and monitoring electroencephalograph. The indicators for monitoring changes in the autonomic nervous system include analgesia nociception index, skin conductance, surgical pleth index and pupil diameter. This article introduces the most important developments and usages of current monitoring methods for noxious stimulation, which have their own advantages and disadvantages. There are currently no validated objective assessment of nociception that can be recommended for clinical use.