Earthen sites are an important part of cultural heritage in China, and more and more scholars have focused on and participated in their conservation. In order to clarify the research progress of the conservation work for earthen sites in China in the past 30 years and to predict the future research trends, the method of bibliometrics combined with two types of literature visualization analysis software—VOSviewer and CiteSpace—were used to analyze 331 papers of CNKI from 1990 to 2021. The results show that the number of published papers on the conservation of earthen sites presents a rising trend in recent 30 years. Currently, academic teams with the characteristic of “small concentration and large dispersion” have been formed. There has developed a relatively complete research network, the topics of which include deterioration, reinforcement materials, anchorage technology, stability, conservation conception, etc. The research on the conservation of earthen sites in the past 30 years can be divided into three stages:1) exploration of the concept of earthen site conservation and construction of theoretical frameworks; 2) research on the conservation materials and technologies for earthen sites; 3) research on the deterioration mechanism of earthen sites. The main research trends corresponding to the three major research topics are as follows:1) improving the deterioration classification and quantitative grading of earthen sites; 2) building systemic evaluation of the conservation materials and technologies for earthen sites; 3) conducting research on mechanisms of deterioration under multi-field coupling, as well as quantifying physical and mathematical models of deterioration and developing forecasting models with multidisciplinary references.