1. A method for content categorization, comprising: transmitting, by a content categorization request entity, a categorization ability negotiation request to a content categorization providing entity to request categorization ability of the content categorization providing entity; receiving, by the content categorization request entity, the categorization ability of the content categorization providing entity from the content categorization providing entity; receiving, by the content categorization request entity, the categorization ability negotiation request from the content categorization providing entity; returning, by the content categorization request entity, the categorization ability supported by the content categorization request entity to the content categorization providing entity; requesting, by the content categorization request entity, content categorization from the content categorization providing entity according to the categorization ability; and receiving, by the content categorization request entity, a categorization result of the content from the content categorization providing entity.