Abstract: HThis paper is a record of our observation on the stages of development of Plasmodium Jalciparum in Anopheles dirus. The malarial parasites were derived from 5 infected pa-tients living in Guizhou Province and used to infect 8 batches of An,dirus. The morpho-logy of various developmental stages studied under light microscope and their average size were as follows: Microgametes were filament-shaped, 13.31 ±2.Z2μm; macrogametes and zygotes oval or round, 4.36 ± 0.59μm and 3.39±0.39μm respectively; ookinetes banana shaped, 13.56 ± 0.80μm× 2.90± 0.48μm; oocysts ovoid or spherical in shape, the smallest one being 7.086μm in equivalate diameter (2 days old) and the largest one-72.60μm (11 day old); slender sporozoites measured 10.625 ±0.82μ× 1.179± 1.3μm. The late sporogonic stage of P. fulciparum was observed with scanning electron mi-croscope. The sporozoite buds developed on the surface of the sporoblast bodies, being round or elliptic or irregular-shaped. The anterior end of sporozoites was truncate and sometimes a micropyle could be seen at a distance 1/3 from the anterior end.A description was given of the different characteristics of the macrogametes and zygotes, together with the arrangement of the pigment granules of oocysts.