The work aims to design and develop TC-I type transport cask to transport small quantities of radioactive materials. The transport cask was designed in accordance with the stipulation of B(U) type package described in GB 11806—2004 Regulations for the Safe Transport of Radioactive Materials. The transport cask had a nested structure of three layers with three main components: drum, heat-resistant and vibration-resistant materials and containment vessel. The material of drum and containment vessel was stainless steel 304, and the main component of heat-resistant and vibration-resistant materials was spruce. The TC-I type transport cask designed was assessed with transport accident condition tests, including water immersion test, mechanical test and heat resistance test. The leak test results before and after the test showed that, the performance of such cask met the requirements of content leakage limit in GB 11806—2004. A B(U) type transport cask for radioactive materials is successfully designed. The transport cask can guarantee the transportation safety of radioactive materials in the stipulated transport accidents.