目的：探讨异盘并殖吸虫在大鼠体内发育的多态性及其主要寄生部位，确定大鼠的宿主性质。方法：囊蚴经口感染大鼠后，用生理盐水逸出法，分离组织中童虫或直接从肺和肝脏虫囊内取虫，测量虫体大小，染色并摄影。结果：异盘并殖吸虫感染大鼠１４ｄ时，虫体侵入肝脏、肌肉和腹腔；３０ｄ时，发育出现分化。体腔中虫体发育迅速，成为具有生殖器官雏形的大型童虫，肌肉中虫体发育迟缓；感染７０ｄ以后，大鼠的肺、肝和胸壁有虫囊形成，囊内虫体发育成熟且产卵。９只大鼠感染７０ｄ后，其中７只在肝脏检获多个虫囊，最多达１１个虫囊。囊内虫体发育良好，成熟率为７８．６％－１００％，最大虫体为１６ｍｍ×８ｍｍ。肝脏严重受损，表面凹凸不平，纤维结缔组织增生，肝细胞变性坏死。分布于肌肉中的虫体占３２．６％－８２．４％，始终保持小型童虫状态。感染后１５６ｄ，虫体仍无发育，其大小为９１４．８７μｍ±７８．２１μｍ×５２５．３４μｍ±７６．２６μｍ，排泄囊内充满黑色颗粒。结论：异盘并殖吸虫在大鼠体内发育呈多态性且多部位寄生，大鼠为其终宿主及其转续宿主。 Objective: To investigate the polymorphism of Paragonimus parasitoid in rats and its main parasitic sites to determine the host properties of rats. Methods: The metacercariae were infected orally by rats, then the saline solution was used to separate the schistosomula from the tissues or the worms directly from the lung and liver. The size of the larva was measured, and the staining and photography were performed. Results: Paragonimus infection in rats 14d, the parasites invade the liver, muscle and abdominal cavity; 30d, the development of differentiation. The body of the rapid development of body worms, reproductive organs become a prototype of large-scale squirrels, muscle larvae of insects; 70d after infection, the rat lung, liver and chest wall with worm capsule, cystic worm body maturity and spawning . After 9 rats were infected for 70 days, seven of them were seized in the liver and up to 11 blastocysts. The larvae developed well, the maturity rate was 78.6% -100%, the largest parasites were 16mm × 8mm. Serious damage to the liver, the surface uneven, fibrous connective tissue hyperplasia, liver cell degeneration and necrosis. Distribution of worms in the muscle accounted for 32.6% -82.4%, and always maintain the status of small squirrels. At 156 days after infection, the parasites still did not develop and their size was 914.87μm ± 78.21μm × 525.34μm ± 76.26μm. The excretory vesicles were filled with black particles. CONCLUSION: Paragonimus parasitoidis is polymorphic in rats and parasitized in many parts. The rats are the final host and the host for reevolution.