OBJECTIVE To study the pyrogenic pattern of endotoxin injected by different ways in rabbits， and to calculate the pyrogenic threshold dose， thus providing reference for better control on the quality of injections. METHODS Following the requirements of Pyrogen test in Chinese Pharmacopoeia 2010， the rabbits were injected five different doses of endotoxin through different delivery ways. Heating curves were drew， and analyzed. Through curve fitting the fever threshold doses were calculate. RESULTS The pyrogenic threshold dose of endotoxin in rabbits was 45.24 EU·kg-1 after subcutaneous injection. The maximum temperature rising appeared between 3 and 4.5 h after injection， and the fever lasted for 0.5-4.0 h. For intramuscular injection， the pyrogenic threshold dose was 25.97 EU·kg-1.The maximum temperature rising appeared between 2.5 and 4.5 h， and the fever lasted lasted for 0.5-3.0 h.For intramuscular injection. The pyrogenic threshold dose of endotorin was 1.8 EU·kg-1.The maximum temperature rising appeared between 4 and 5.5 h， and the fever lasted for 0.3-1.5 h. CONCLUSION The pyrogenic pattern of endotoxin in rabbits are quit different when injected through different ways.