A large number of CdSe nanorod-assembled microtubes are prepared via a hydrothermal method in an ethanolamine-PEG solution. The tubes with inner diameters of 900 nm and lengths of 5-50 mu m are composed of well-aligned nanorods around 300-nm long. It was found that both the solvent ethanolamine and surfactant PEG-20000 play a key role in the formation of nanorod-assembled microtubes. Ethanolamine as a mild reducing agent was used to reduce SeO2 to produce Se2-. The optimal conditions to produce CdSe microtubes are that the volume ratio of ethanolamine to water is 1:4 and that the quantity of PEG is 3.0g. The possible formation mechanism of CdSe microtubes is also discussed.