Observational studies show that there are some gas clouds which are commonly denser than interstellar medium. They are called as“molecular clouds”. Massive stars are formed in these dense molecular clouds, because compact and ultracompact H II regions can form. Theoretically, a Str¨omgren sphere will form if a new massive star with ionizing radiation is born in a uniform medium. However, observations at radio frequencies and infrared radiation show that there are few spherical H II regions. The surveys for compact and ultracompact H II regions in molecular clouds show that part of these embedded H II regions have a cometary morphology. Other observations demonstrate that shells around H II regions are related to star formation, and different morphologies might make a different influence on the evolution results. As quite a lot of non-spherically cometary-shaped compact H II regions were observed in recent years, some researchers have established a number of hydrodynamic models in order to explain the causes of these phenomena. These efforts are helpful in understanding the evolution of compact H II regions and the formation of massive stars. In this article we present the numerical models and calculation methods of cometary-shaped compact H II regions, the contrast between champagne models and bow shock models, and the future development of the field.%研究表明，在新形成大质量恒星辐射的影响下，分子云中会形成高密度的H II 区。近年来观测到一些非球对称彗星状致密H II 区，学者们为了解释这类目标的产生，先后建立了一系列H II 区动力学模型。这些工作有利于进一步认识致密H II 区的形成和演化及大质量恒星的形成。这里介绍了彗星状致密H II 区的模型模拟和计算方法方面的研究进展，阐述了香槟流和弓形激波两种解释模型的异同，以及该领域未来的发展方向。
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