The invention discloses a spherical Co(OH)2 composite electrode material and a preparation method thereof. The method comprises the following specific steps of (1) ultrasonically mixing a cobalt resource, a surfactant, deionized water and alcohol to obtain a mixed solution; (2) shifting the mixed solution obtained in Step (1) into a hydrothermal reaction kettle to be subjected to a hydrothermal reaction and performing natural cooling to a room temperature after reaction completion to obtain reaction liquid; and (3) centrifuging the reaction liquid obtained in Step (2), collecting a deposit and then performing washing and drying to obtain the three-dimensional spherical Co(OH)2 material. The three-dimensional spherical Co(OH)2 composite material obtained by ultrasonic and hydrothermal treatment methods is good in thermal stability, high in crystallization degree, simple in preparation method, low in cost, high in pattern controllability and environment-friendly, and is one of ideal energy source materials.