The spherical calcium borate which was well-distributed nano-particles used as lubricating oil additives had been preparated by neutralization-precipitation method. The composition and surface morphology of samples were characterized by XRD and SEM.The refined oil was produced from a certain percentage of the sample dispersed in lubricating oil. the dispersion and stability of lubricants were characterized by standing observation. The performance of lubrication oil was examined by heavy-duty vehicles and industrial gear oil test. And the results showed nano calcium borate additive had good dispersion, stability and anti-wear friction properties.