The tendency to lower power inputs on reception cryoproducts results for development of more effective technological circuits and new machine equipment. With that view to modern cryogenic plants apply expander-compressor unit (ECU), allowing to use energy of expansion of air’ part for increase of its pressure in compressor step. Includion ECU in structure of cryogenic plants is justified when cycles of low pressure are realized. In plants of average and high pressure as shown in article it is necessary to apply two-stage expansion. The circuit of liquefier with ECU representing incorporated in one unit compressor and two expander steps is described. The compressor step is used for increase of pressure before expander of low pressure, i.e. for compression of stream after expander of high pressure. It is shown that in the offered circuit with ECU the factor of liquefaction on 34,2 % is higher than in Claude’s cycle. ECU for such cryogenic plants is necessary to create on a basis of multiple construction with compressor step as the multistage compressor.