In solving integral equations with logarithmic kernel which arises from the
boundary integral equation reformulation of some boundary value problems for
the two dimensional Helmholtz equation, we combine the Galerkin method with
Beylkin's ([2]) approach, series of dense and nonsymmetric matrices may appear
if we use traditional method. By appealing the so-called periodic quasi-wavelet
(PQW in abbr.) ([5]), some of these matrices become diagonal, therefore we can
find a algorithm with only O(K(m)2) arithmetic operations where m is the highest
level. The Galerkin approximation has a polynomial rate of convergence.