In the paper, we suggest widening the scope of the cryogenic atomic-force microscopy in order to determine the Young modulus of biological objects over a temperature range stretching from 30 to 300 K. A new technique assumes some modification of the arrangement for the optical system recording the probe position in the cryogenic atomic-force microscope and making measurements of approach and retraction force-distance curves under these conditions. The Young modulus is determined from the obtained data by the calculation taking into account the temperature dependence of a cantilever spring constant. As an example we have obtained a temperature dependence of the Young modulus for polylysine in the temperature range stretching from 60 to 300 K (RT) using the proposed technique.