This paper presents the fabrication procedure and characterization of cobalt nanostructure-based microelectrodes for phosphate detection. Cobalt thin films with different plane, nano-scale structures were obtained on gold microelectrodes by adjusting the parameters of electrodepositing method. The result of the fabrication was examined by XRD and SEM, showing the crystal direction and surface morphology of the electrodeposited cobalt layer. Electrochemical characterization of these microelectrodes was performed. The electrodes deposited under different parameters present a linear response in the range from 10-6mol/L to 10-2mol/L with a slope ranging from -19 to -17.6mV/decade. The potential response becomes stable in 200s after the electrode was put into the phosphate solution. It could be assumed that the difference in surface morphology of the electrode caused by changing depositing parameters may have little affection to the response to phosphate.