  The renormalization-group method is used to analyze the low-temperature
behaviour of a two-dimentional, spin-$s$ quantum Heisenberg ferromagnet. A set
of recursion equations is derived in an one-loop approximation. The
low-temperature asymptotics of the correlation length and the uniform
susceptibility are obtained. For small spins ($s= 1/2,1$) the results are
essentially different from those in the spin-wave theory.
