Cloud manufacturing is a new service-oriented intelligent manufacturing model, which contains plentiful knowledge to support service system operating, and the manufacturing resources and capabilities are shared (as services) through the internet. However, there is a lack of in-depth research in knowledge cloud capability service, influence factors and its evaluation approach. The comprehensive evaluation system of the whole features was established for knowledge cloud capability service, and a new quantificational knowledge cloud capability evaluation approach was presented based on cloud reasoning. The expected value and hyper entropy of knowledge capability cloud were used to evaluate the satisfaction of service performance by cloud processing the evaluation indicators, and a cloud reasoning controller was designed to depict the satisfaction change style of knowledge capability, which provided support for the intelligent shared service of manufacturing resources and capability in cloud manufacturing system, e.g. design as a service, simulation as a service, production as a service, assembling as a service, and testing as a service. The result of simulating experiments showed that the validity and effectiveness of the presented approach provided beneficial exploration for evaluating knowledge cloud capability service of cloud manufacturing.