Abstract: The inputs of carbon dioxide from anthropogenic activities to ocean through the sea-air interface exchange disturbs the balance of seawater carbonate system, resulting in ocean acidification (OA). OA affects the physical and chemical properties of both seawater and marine pollutants, which significantly regulates the physiological processes of planktonic algae living on the surface of ocean. As the main primary producers, the physiological function and processes of marine algae play an important role in marine ecosystem. We reviewed the underlying mechanisms of OA on the three key physiological processes of photosynthetic carbon fixation, calcification and nitrogen fixation of marine microalgae. OA could alter environmental factors (e.g., solar radiation, temperature, nutrient elements) and typical marine contaminants (e.g., organic contaminants, heavy metals, microplastics). We further summarized the effects of these factors on the regulation of physiological processes of microalgae. Finally, current research status and prospects for future research were addressed. This review provided important information for better understanding the potential impacts of OA on marine ecosystems.

Key words: ocean acidification, marine microalgae, marine contaminant, environmental factor, physiological process