The flux of nitrogen in cooling systems can be controlled by using a special shape memory alloy to save the consumption of liquid nitrogen. To develop such kind of shape memory alloy, the relation between the microstructure and M s temperature in Cu–Al–Mn alloy was studied. It was found that the addition of Al and Mn would decrease the M s temperature. By adjusting the chemical compositions and heat treatment process, it is available to make the Cu–Al–Mn alloy with shape memory effect at about 100K, and in turn to design a valve of nitrogen flux by the alloy.