Abstract: To determine the operating characteristics of ejector， evaluate the numerical model calculation accuracy and improve the ejector pump theory， an experimental system of small steam jet refrigeration was set up. The relationships between the steam jet pump performance and working steam pressure， suction pressure， the back pressure of the ejector were studied by using experimental method. The experimental results show that the secondary fluid flow rate and ejector coefficient (entrainment ratio， ER) increase firstly to the maximum and then decrease gradually with increasing the working steam pressure. With increasing suction pressure， the secondary fluid flow rate and the ER increase. The ER keeps a constant value in a certain range of back pressure and declines sharply when back pressure is bigger than the critical back pressure. It is important to understand the pumping characteristic of steam jet pump deeply based on the experimental research， and the experimental data can be used to optimize steam jet pump’s structure.

Key words: steam jet refrigeration system, steam flow rate, ejector coefficient, experimental research