Tomato spotted wilt virus (TSWV) is a bacterial virus that seriously harms the growth of tobacco. In order to realize the rapid detection of TSWV, monoclonal antibody to TSWV-NP protein was prepared and characterized, and colloidal gold immunochromatographic test strips were established that can be used to detect TSWV. In this study, the monoclonal antibody to TSWV-NP protein was labeled with colloidal gold, and the reaction conditions were optimized to establish a colloidal gold immunochromatographic test strip assay, and the detectability, accuracy, and specificity of the test strip were evaluated. The detection limit of the test strip for TSWV-NP protein was 0.1 μg/mL, and there was no cross-reactivity with tobacco bunchy top virus, potato Y virus, and tobacco mosaic virus, which had excellent specificity. The results of the colloidal gold test strip and the RT-PCR result method were compared with the actual samples, and the total conformity rate of the two was 95%, and the positive conformity rate was 93.3%.