Abstract: Soil biodiversity has been one of the foci in the soil ecological research field. Soil biota can change the physical, chemical and biological characters of soil in different ways. In farmland ecosystems, soil organisms are main regulators in the decomposition, nutrient mineralization and other ecological processes of soil. Soil nematodes are the most abundant metazoan, which have various types of life-history and feeding habits, and play a key role in soil food web. This paper introduces the main factors influencing soil nematode diversity in farmland ecosystems, reviews the present situation in the nematode diversity research field and presents the research prospect of nematode diversity in the future. We propose to integrate the life strategy approach and trophic group classification to obtain a better understanding of nematode diversity and their functions, so as to use nematodes as effective bioindicators in farmland ecosystems.