Abstract: Sphere-like and cubic ZnO nanoparticles were synthesized using ZnCl2 and oxammite as raw materials by way of the precipitation reaction through which the precursor ZnC2O4 · 2H2O was obtained and then pyrolyzed. TEM and XRD results showed that they are of crystalline zincite with grain size 25-80 nm. The TG-DTA test was carried out for the precursor. It was revealed that increasing the reaction time and pyrolysis time/temperature will increase the size of primary particles. On the other hand, increasing reaction temperature (below 90°C) will take opposite effect. When the original concentration of Zn²⁺ is below 0.5 mol/L the size of the particles change little (25 nm), but when it reaches 0.7 mol/L the size ascends to 80 nm.