Abstract: Ultra-fine zinc oxalate powders were prepared through precipitation stripping method with Bis(2-ethylhexyl)phosphate(HDEHP) diluted by tetrachloride carbon as an extractant,and oxalic acid ethanol aqueous solution as a re-extractant and precipitator.Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450 ℃.The prepared zinc oxide powders were characterized by TEM,SEM,TG,XRD and FT-IR.The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and photo-layer model.The results showed that some zinc oxide powders were micro-multipore materials with hexagonal crystal and the particle size was around 32 nm.The photocatalytic process was the control step in chemical reaction.The photo catalytic process followed the pseudo-first order kinetics and ·OH concentration inside the photo-layer in different reaction condition were calculated according to the photo-layer model.