Objectives The types of unconventional feeds and their effects on the rumen microflora of cattle were summarized to provide studying basis for the rational utilization of unconventional feeds. Methods The literatures related were consulted and the relevant contents were overviewed. Results The types of unconventional feeds include crops, forestry by-products, and dregs, with abundant resources. Adding the three types of unconventional feeds mentioned above to the daily diet had different effects on the relative abundance of rumen bacteria, archaea, and protozoa in cattle. The addition of crops feed did not affect the dominant bacterial phylum in the rumen of cattle, only changed the dominant bacterial genera and its relative abundance. Adding a certain proportion of paper mulberry and leucaena glauca increased the proliferation of beneficial bacteria in the rumen, while the addition of paper mulberry and bacterial bran reduced the abundance of methane bacteria. Conclusions Part of the unconventional feeds can increase the abundance of beneficial bacteria in the rumen of cattle, promote the decomposition of protein and fiber by rumen microbiota. In practical application, appropriate ratios of addition and combinations of replacement should be considered.