To evaluate the value of Magnetic Resonance Cholangiopancreatography (MRCP), in the diagnosis of cholelithiasis, we randomly assigned 1000 patients with cholelithiasis from The First Hospital of Hohhot City since 2011. All the 1000 patients who were diagnosis of cholelithiasis in the clinical were given MRCP Preoperative. While 94.7% of the patients were examined with Preoperative Liver and gallbladder color Doppler ultrasound at least once, the remaining 5.3% were examined by CT of midsection. The software SPSS 13.0 was used to evaluate the difference of relevance ratio of cholelithiasis between color Doppler ultrasound and CT, as well as the relevance ratio of the variant Biliary system before operation. Among 1000 cases of cholelithiasis patients, patients with only Calculus of bile duct was 177, 676 cases of patients with only cholecystolithiasis, 185 cases of patients with both. The relevance ratio of cholelithiasis was 92.13% in Calculus of bile duct, and 87.50% among patients of cholecystolithiasis. The trail on the other hand analysis the clinical value of MRCP for the variant Biliary system before operation. MRCP is more suitable for the diagnosis of Calculus of bile duct and the judgement of variant Biliary system before operation, it can obviously reduce the occurrence of iatrogenic injury of biliary system, which made MRCP an important reference examination to the cholecystic preservation surgery.