The invention relates to a slewing bearing wearing extent on-line measurement and lubricating grease automatic filling-up method. The method comprises the steps of utilizing the change of a lubricating grease insulating property to judge the change of metal particle content in a lubricating grease, and judging the wear condition of a slewing bearing raceway, so as to indirectly judge the generation and development of the damage of the raceway and be used for optimizing a lubrication condition of a slewing bearing, determining filling-up quantity and filling-up frequency of the lubricating grease according to the wear condition, and realizing the required lubrication of a self-adapting working condition. The method provided by the invention avoids the problem of separation of a wearing extent value of a micrometric displacement measuring method, the problem of self abrasion of a contact-type micrometric displacement transducer, and the problem of insufficient non-contact type micrometric displacement range and poor accuracy, can realize on-line measurement, avoids the problems that the regular fixed point filling-up has the problems of excessive pouring grease or shortage and the like, optimizes the lubrication condition of the slewing bearing, effectively improves the load-carrying capability of the slewing bearing, prolongs the service life, and fills up an industry blank; and the purposes can be realized just by general instrument and equipment such as electric control grease pouring pumps, insulation meters and measuring heads.