Abstract: With the construction of UHVAC/DC lines and the large-scale renewable energy integration in China, more refined rules have been required for the power dispatching, which makes it difficult for the dispatchers to memorize and reason the rules in the current document/text form. This paper analyzed the characteristics and the complexity of the power grid dispatching rules and reviewed the production rule system, which can represent the dispatching rules. Then, a systematic modeling process to develop dispatching rule knowledge model was proposed. The structure of dispatching rule conceptual knowledge model was developed and a decision graph approach was used to represent the model. Decision Model & Notation (DMN) standard was adopted to implement the conceptual knowledge model. In addition, based on the digital twin power grid model, an approach to implement the dispatching rule knowledge model was proposed. The proposed knowledge model was used in the implementation of a dispatching rule digitization system, which has been in production in a provincial power grid in China. Some primary results of the rule digitization system and its potential application scenarios were discussed.