Virgin coconut oil (VCO) is commonly known as one of coconut products in Indonesia. Along with the production, abyproduct coconut milk skim effluent (CMSE) is also generated and could become a potential pollutant for the environment. However the effluent still contain micro and macronutrient that could be utilized for microalgae growth. The purpose of this research was to determine wastewater characterization and to utilize the wastewater as Spirulinaplatensis medium. Cultivation was maintained in pH=9, 2 ppt salinity, for 5 days under flourescent lamp 5000 lux. CMSE was added in different concentration (10-80%v/v) and different synthetic medium reduction (0-50%w/v). The result indicated that 20% v/v medium and 10%v/w synthetic medium provided optimum growth, produced up to 0.206 gr/l dry weight of biomass and contained 39% of protein.