Organic carbon contained in soil organic matter is the largest terrestrial carbon sink on the globe. Quantity and quality of soil organic matter is a major indicator reflecting soil fertility. Moreover, the processes of formation, transformation and stabilization of soil organic matter are closely related to global climate change. Plant residues are the primary source of soil organic matter, of which the decomposition is subject to the impacts of numerous factors. Soil organic matter and microorganisms vary sharply in spatio-temporal distribution, thus affecting turnover of plant residues. Besides, quantity, quality and input pathway of plant residues per se also governs decomposition of the residues. So, mechanisms of the transformation of plant residues into organic matter and its stabilization remain unclear. In this paper, introduction to and discussion on new findings in relevant studies on transformation of plant residues into soil organic matter in recent years is presented, exploration made of contributions of microbe-derived organic matter and plant-derived organic matter to total soil organic matter, and elaboration done of the mechanism of soil microbe driving formation of soil organic matter formation. Besides, in the study, a review is presented of relevant studies on stability of soil organic matter after input of plant residues. In the end outlooks of the researches in this field are discussed in the paper, in expectation of providing certain reference for future researches on scientifically improving soil carbon sequestration capacity.