Clubroot caused by Plasmodiophora brassicae Woronin is a globally prevalent soil-borne disease posing a severe threat to the yield and quality of Brassica crops. Due to the violent physiological differentiation and biotrophic characteristics exhibited by P. brassicae, evaluating the pathotypes of P. brassicae in different regions is crucial for breeding Brassica crops with disease resistance and planning the crop cultivation pattern. Accurately assessing the number of P. brassicae resting spores in the soil is instrumental in predicting the risk levels of clubroot in the fields, laying a foundation for subsequent selection of control methods and evaluation of their effectiveness. This paper briefs the methods for identifying P. brassicae pathotypes and detecting and quantifying the resting spores in the soil. Additionally, we propose a single-cell sequencing technique with potential application in the study of P. brassicae pathotypes and analyze the feasibility of recombinase polymerase amplification (RPA) in the detection and quantification of P. brassicae. The aim of this paper is to offer a theoretical foundation and methodological reference for the effective control of clubroot while providing new insights and solutions for the identification and detection of P. brassicae.