Diagnosis and surgical procedures were studied in this paper. Twentyfive cases of insulinoma were treated surgically from 1970 to 1997, in which 10 patients had Whipple′s triad so that the early diagnosis could be made. The sites of tumours were found in 10 out of 12 undergoing. Selective celiac angiongraphy with the accuracy rate of 83%, but B-ultrasonography and CT gave only 10% (4 out of 25) and 40%(8 out of 20) respectively. In this series, 5 cases underwent bodytail pancreatectomy and 20 cases enucleation of insulinoma. Blood glucose levels were tested during operation in 15 cases, and they all reached the normal level one hour after the tumours were completely removed. The authors consider that Whipple′s triad is the main basis in diagnosis of insulinoma. The selective celiac angiongraphy play an important role in detecting and locating the tumour. If diagnosis is made, surgical operation should be taken. The blood glucose monitoring during operation is the hallmark for complete resection of insulinomas.