Abstract: Objective To analyze and explain how to treat a patient with deep caries based on best evidence. Methods Used dental caries and excavation as key words to search OVID-All EBM reviews-cochrane DSR, ACP journal club, DARE, and CCTR（4th Quarter 2006） to find the best clinical evidence and evaluated the quality of evidence. Results According to the evidence, we found that partial caries removal would appear to be preferable to complete caries removal in the deep lesion, in order to reduce the risk of carious exposure. We found no evidence that partial caries removal is deleterious in terms of signs and symptoms of pulpitis or necrosis in the immediate to long term. It needs further clinical trial to decide whether cavity need re-entered at a second visit to allow the remaining decay to be removed. Conclusion Partial caries removal in symptomless, primary or permanent teeth reduces the risk of pulp exposure. We found no detriment to the patient in terms of pulpal symptoms in this procedure