Document-level entity relation extraction aims to extract all relations between entity pairs from unstructured text. Aiming at the problems of multi-mention entity, long-distance entity Relation and complex relation reasoning, this paper proposes a document relation extraction Model TSDRE (Three stage document Relation extraction Model) based on text coreference resolution and relation reasoning. Firstly, the CorefQA model was used to resolve the referential pronouns in the document. Secondly, the document was cut by sentence, and the PRGC model was used to extract the relationship at sentence level. Finally, the information of entity pairs that may have complex relationships, relationship reasoning information and evidence statements are taken as known information, encoded and used as the input of the model, and the BERT model is used to reason about complex relationships and determine the possible relationship categories of entity pairs. The experimental results show that the proposed model is at least 0.18,0.15,0.21 higher than other comparison models in the three indicators of validation set F1, test set F1, and lgnF1. TSDRE can extract the entity pair relationship information contained in the document more accurately and comprehensively.