Abstract: The study focused on the acid fuchsin stain technology and histology of two obligate parasitic fungi with their hosts.The infection progress and histology change of Gymnosporangium yamadai infecting Chaenomeles lagenaria were described,the interaction histology between vesicular-arbuscular mycorrhiza and Oxalis corniculata L.was also studied.VAM can infect the host from root-cap and form a mycelia-net.The result indicated the method is fine for histological studies.