Magnesium oxide (MgO) is an important oxide material that has many applications such as catalysts, catalyst supports, adsorbents, refractory materials, pharmaceuticals [1] and toxic waste remediation [2].MgO fibers were fabricated from magnesium acetate sol by electrospinning previously [3].However, it is liable to be pulverization and becomes unconsolidated after MgO fibers calcined at high temperatures.In this study, the MgO precursor sol was optimized to ameliorate the microstructure of MgO fibers and obtain compact grain structure, The optimized sols were composed of magnesium acetate and magnesium citrate (abbreviated as MA and MC hereinafter, respectively) whose decomposition temperature ranges were different.MA and MC were chosen to confect the precursor sols in different proportions.The fibers were prepared through electrospinning equipment by sol-gel dry-spinning method.TG/DSC and IR spectrum were used to characterize the thermal decomposition process of the precursor fibers.The crystallization of the precursor fibers was studied by XRD.The morphology of MgO fibers was observed by SEM and found to be largely influenced by the ratio of MA and MC in precursor sols.After heat-treated at 600 ℃, 1000 ℃, MgO fibers showed good morphology and microstructure, which were better than the fiber processed from the sol formed only by MA.When the weight proportion of MC was 30~50%, finer MgO fibers could be obtained.