Abstract: A series of 3-(dialkylamino) alkoxy-4 (5)-t-butylphenyl N, N-dimethylcarbamates(Ⅰ and Ⅱ), which are the nuclear alkylated derivatives of 3-(2-dimethylamino) ethoxyphenyl N, N-dimethylcarbamate (CUI XING AN) was prepared as potential anticholinesterase agents. Preliminary screening tests showed that the introduction of t-butyl group in CUI XING AN and its homologs decreased the toxicity and anticholinesterase activity. Compounds of type Ⅰ have increased protective activity against organophosphorus poisoning.