Protected areas (PAs) are a research hotspot in biodiversity conservation. Conservation effectiveness of PAs has been a subject of numerous domestic and international studies. This paper aims to provide a comprehensive understanding of the state of domestic and international research on the effectiveness of PAs. We conducted advanced retrievals on Web of Science (WOS) and China National Knowledge Infrastructure (CNKI), resulting in a total of 4,752 English articles and 438 Chinese articles. Using VOSviewer and Citespace for literature visualization, publication quantity, trends, and hotspots in domestic and international publications were analyzed. The results are as follows: (1) both domestic and international studies on conservation effectiveness of PAs showed an overall increasing trend, which underwent a starting stage before 2005, an exploratory stage from 2005 to 2010, and a rapid development stage from 2010 to the present; (2) International research hotspots on the conservation effectiveness of PAs included management effectiveness, biodiversity, ecosystem services, influencing factors (land use, climate change, human disturbance, etc.), and sustainability. The hotspots of the conservation effectiveness of PAs in China could be divided into ecosystems and biodiversity, management effectiveness, sustainable development, and influencing factors. (3) A comparison of English and Chinese literature revealed differences in temporal scale and focus. International research focused primarily on national parks and forest ecosystem protection, whereas domestic research centered on nature reserves and wetland ecosystem protection. Moreover, ecosystem service protection and the impact of climate change in Chinese literature were limited. In conclusion, the study on conservation effectiveness of PAs is essential to understanding the status and changes of biodiversity and ecosystem services in these areas, identifying and addressing key constraints, and improving their management quality. Currently, China is in a crucial stage of constructing a PA system with national parks as the main component. According to the evolution trend, research hotspots, and comparisons between domestic and international research, this paper outlines the research outlook for the subject of conservation effectiveness of PAs in China. First, it is essential to strengthen fundamental research on biodiversity and ecosystem services within PAs. Then, monitoring and evaluation techniques improvement and conducting sustainable development-oriented quantitative research should be investigated. Furthermore, it is fundamental to enhance effective management of PAs based on the conservation assessment of PAs. We believe that this paper could servs as a reference for subsequent research on the effectiveness of PAs, aiming to promote the development of the research field in China, and provide a scientific basis for enhancing the management quality of PAs in the country.