Rice false smut, caused by Ustilaginoidea virens, is a devastating disease that greatly reduces rice yield and quality.  However, controlling rice false smut disease is challenging due to the unique infection mode of U. virens.  Therefore, there is a need for early diagnosis and monitoring techniques to prevent the spread of this disease.  Lateral flow strip-based recombinase polymerase amplification (LF-RPA) overcomes the limitations of current U. virens detection technologies, which are time-consuming, require delicate equipment, and have a high false-positive rate.  In this study, we used a comparative genomics approach to identify Uv_3611, a specific gene of U. virens, as the target for the LF-RPA assay.  The designed primers and probe efffectively detected the genomic DNA (gDNA) of U. virens and demonstrated no cross-reactivity with related pathogens.  Under optimal conditions, the LF-RPA assay demonstrated a sensitivity of 10 pg of U. virens gDNA.  Additionally, by incorporating a simplified PEG-NaOH method for plant DNA extraction, the LF-RPA assay enabled the detection of U. virens in rice spikelets within 30 min, without the need for specialized equipment.  Furthermore, the LF-RPA assay successfully detected U. virens in naturally infected rice and seed samples in the field.  Therefore, the LF-RPA assay is sensitive, efficient, and convenient, and could be developed as a kit for monitoring rice false smut disease in the field.