Saline lakes are widely distributed on the surface of the earth, with a relatively high density of salt lakes recorded in China. Saline lakes are often productive and comprise an important part of the highland ecosystem, since they harbor many novel prokaryotic microorganisms under harsh environmental conditions. However, little research has been conducted in these systems, and understanding about the community diversity and dynamics of picophytoplankton assemblages in such environments is limited. Picophytoplankton, defined as phytoplankton with a diameter less than 0.2-3 μm and composed of both prokaryotes and eukaryotes, not only play a crucial role for primary productivity in marine ecosystems, but also in saline lake ecosystems. Recent survey data suggest that picophytoplankton contribute from 53%-68% of the productivity in the total phytoplankton community in Lake Bogoriau and Lake Nakuru in East Africa. Biodiversity research of picophytoplankton has mainly focused on hypersaline lakes, such as solar salterns, saline ponds, and soda lakes. The most dominant taxa included Arthrospira, Phormidium, and Aphanothece, known as cyanobacteria in hypersaline lakes. Molecular analyses revealed significant genetic diversity in hyposaline soda lakes. After cloning and sequencing, the results found that the majority of the retrieved sequences belonged to prokaryotic picophytoplankton, while the others showed high similarity with eukaryotic algal plastids. Research on the picophytoplankton community patterns and seasonal succession in saline lakes has been attracting the attention of more and more scientists in recent years. Total dissolved solids were identified as the predominant factor structuring the spatial distribution of picophytoplankton. Light intensity, nutrient composition, and temperature also affected the spatial distribution and community composition of picophytoplankton. In this paper, the biodiversity patterns, spatial distributions, and community succession of picophytoplankton within different geographical regions were compared and summarized through literature reviews. Our results highlight the importance of more comprehensive investigation about the diversity, distribution, and ecological role of picophytoplankton in saline lakes at the national level in China.