Abstract: Some tool-drugs, which affect transmitters in the central nervous system, were used to explore the analgesic action of crystal-8 related to cholinergic system and monoamine transmitters. The analgesic action of crystal-8 was not affected by scopolamine,physostigmine, apomorphine and haloperidol, but was antagonized by reserpine. The analgesic action of crystal-8 was potentiated by 1-dopa (50 mg/kg, ip) and dl-5-HTP (56mg/kg, ip) after intraperitoneal administration of decarboxylase inhibitor (RO-4-4602), or dopamine β-hydroxylase inhibitor DDC Therefore, the authors propose that the analgesic action of crystal-8 may be related to the level of DA and 5-HT in brain, especially DA.