The three-dimensional flower-like zinc phosphate [Zn 3 (PO 4 ) 2 ·4H 2 O] micro-nanostructures was synthesized by a microwave-assisted sonochemical method in the absence of template under ambient conditions. The effects of reaction temperature of water bath and reactant concentrations on the particle size and morphology of flower-like zinc phosphate were studied. The scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy were used to characterize the samples. The results showed that the three-dimensional flower-like zinc phosphate is composed of self-assembled two-dimensional nanosheets. The average thickness of two-dimensional nanosheet was 35–40nm, and 5–12 layers of nanosheets formed a layered flower with an average thickness of 220–540nm. The reaction temperatures of water bath and reactant concentrations are the key factors to synthesize perfect three-dimensional flower-like zinc phosphate. The self-assembly is main growth mechanism to form the flower-like zinc phosphate.