A facile and selective route based on a precipitate slow-release controlled process was developed to produce both high-quality MnSe2 and alpha-MnSe uniform microcrystals in aqueous solution at low temperatures (100-180 degreesC). The magnetic properties of the two samples were investigated in detail. This synthetic method will have potential applications in material science, especially in fabricating diluted magnetic semiconductors. These uniform microcrystals might be useful in microdevices, seed crystals, and magnetic cells.