We study the Ising model defined on a class of hierarchical lattices in ord
er to analyze the geometric effects on the critical exponents and on the gl
obal scaling properties of the Julia sets consisting of the Yang-Lee zeros
of the partition functions. Using the exact renormalization map of the mode
l with an external field we study how the critical behaviors, including the
location of the critical temperature and the critical exponents, vary with
the geometric structure. The generalized dimensions D-q and the sigularity
spectra f(alpha) of the Julia sets of the renormalization maps for differe
nt hierarchies are calculated, and variations caused by their geometric str
ucture are also discussed.