The influence of the choice of ethanol-water volume ratio, concentration of zinc salt, and ZnO buffer layer on the formation and morphology of Zn5(OH)8(NO3)2·2H2O grown from the hydrothermal route was systematically discussed. Experimental results suggested that Zn5(OH)8(NO3)2·2H2O rectangle sheets and Zn5(OH)8(NO3)2·2H2O upright-standing plates were obtained by limiting ethanol-water volume ratio. The concentration of zinc salt was crucial for getting phase-pure Zn5(OH)8(NO3)2·2H2O. The presence of ZnO buffer layer could lead to the that chemical composition of product grown on the substrate was totally different from the product grown in the solution. Possible formation mechanism of Zn5(OH)8(NO3)2·2H2O was also studied. Raman spectrum of Zn5(OH)8(NO3)2·2H2O displays a complex behavior with four modes, which can be assigned to the vibrational modes of Zn–H–O, Zn–O, H2O-nitrate, and nitrate. Porously ZnO rectangle sheets were obtained by thermal treatment of Zn5(OH)8(NO3)2·2H2O rectangle sheets.