Abstract: As massive data generated in large scale e-Science projects such as High Energy Physics (HEP) and astronomical observation (e-VLBI) needs to be transported internationally over fast long distance network, high performance transport protocol is needed. Based on UDP, some reliable transfer protocols are designed. This research mainly studies the principles of these protocols and compares their performance by experiments. It is found that they far outperform TCP, but still have some limitations and can’t satisfy the requirement of bulk data transfer perfectly.