Abstract: AIM: To look for the new kind of analgesic compounds with higher activity and lower toxicity. METHODS: Six 1,1′-diacyl-4,4,4′,4′-tetraalkyl dipiperazinium dibromides(IVa～f) were synthesized from acylation of 1-methyl piperazine with corresponding diacide chloride(IIa～d), and then quaternization by different alkyl bromide. RESULTS: Preliminary biological activity test showed that all the tested compounds IVa～f showed obvious analgesic and sedative activity, especially for IVe (dose 20 mg.kg^-1, analgesic activity 80.3%, and sedative activity 95.3%) and IVf (dose 0.5 mg.kg^-1, analgesic activity 75.5%, sedative activity 53.8%). CONCLUSION: The distance between two nitrogen cations affects the biological activities and the toxicity distinctively. When n=4, the analgesic and sedative activities are best in IVa～d, the toxicity decreases as the n decreases. The introduction of benzyl group increases the analgesic and sedative activities and decreases toxicity obviously.