Raw product MnSO4·H2O from manganese mines of Guangxi was utilized to synthesize cryptomelane by an inexpensive and practical method. K_brinesstie was prepared by oxidation of the mixture of MnSO4 and KOH solutions with soluble oxygen and excessive OH-, and then transformed to cryptomelane during the heating process. According to the experimental results, the optimal operational parameters were confirmed: 0.2 M MnSO4·H2O and 1 M KOH in 500 mL system at room temperature reacted for 3 hours with 30L/min air flow rate and 100r/min stirring rate; the precipitate was washed again and again till pH=12， and dried and ignited at 600℃ for 1 hour. The results obtained provide fundamental data for further processing of manganese product on a large scale.