Abstract: The temperature characteristic of multi-injection taking place in the high pressure common rail (CR) system plays a major role in controlling of multi-injection. A detailed experimental study on temperature characteristic of multi-injection is conducted on the high-pressure common rail multi-injection test bench. The law of temperature influence on characters of period and amplitude of water hammer pressure wave and injection quality is summarized. The period of pressure wave is increased with temperature. And the max amplitude of pressure wave is increased at first and then decreased with temperature. Temperature characters of water hammer pressure wave was analyzed based on sound speed and water hammer phenomenon. The temperature characteristic of multi-injection fuel quality fluctuation is caused by the temperature influence on both pressure wave and injection characteristic.