The changes of natural conditions and human activities have not only intensified soil acidification and expanded the area of acidic soil but also seriously affected soil nitrogen cycle. As a rate-limiting step of nitrification, ammonia oxidation is the core of the global nitrogen cycle, which has attracted extensive attention. Exploring ammonia oxidation in acidic soil and the involved functional microorganisms is of great significance for deciphering the nitrogen cycle mechanism and promoting soil nutrient cycling. This paper summarized the mechanisms of ammonia oxidation in soil and compared the relative contributions of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and complete ammonia oxidizers (Comammox) to ammonia oxidation in acidic soil. Then, we analyzed the effects of microbial endogenous function differences and environmental factors such as pH and substrate concentration on the abundance, activity, and community structure of ammonia-oxidizing microorganisms. Finally, the future studies about ammonia-oxidizing microorganisms were prospected. This paper is expected to provide scientific references for future research on ammonia oxidation in acidic soil, as well as the application and practice of microbial remediation.