The rapid and accurate diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the early stage of virus infection can effectively prevent the spread of the virus and control the epidemic. Here, a colorimetric and fluorescent dual-functional lateral flow immunoassay (LFIA) biosensor was developed for the rapid and sensitive detection of spike 1 (S1) protein of SARS-CoV-2. A novel dual-functional immune label was fabricated by coating a single-layer shell formed by mixing 20 nm Au nanoparticles (Au NPs) and quantum dots (QDs) on SiO2 core to produce strong colorimetric and fluorescence signals and ensure good monodispersity and high stability. The colorimetric signal was used for visual detection and rapid screening of suspected SARS-CoV-2 infection on sites. The fluorescence signal was utilized for sensitive and quantitative detection of virus infection at the early stage. The detection limits of detecting S1 protein via colorimetric and fluorescence functions of the biosensor were 1 and 0.033 ng/mL, respectively. Furthermore, we evaluated the performance of the biosensor for analyzing real samples. The novel biosensor developed herein had good repeatability, specificity and accuracy, which showed great potential as a tool for rapidly detecting SARS-CoV-2. •The composite nanospheres with colorimetric and fluorescent dual-functional and excellent stability was synthesized.•The sensitivity of the colorimetric signal and the fluorescence signal of the SiO2@Au/QDs-based LFIA strip was 10-fold and 300-fold higher than those of Au-based LFIA strip, respectively.•The novel biosensor for rapid antigen detection demonstrated excellent specificity and reproducibility, RSD< 7.16%.•The LOD of the novel LFIA biosensor for the inactivated SARS-CoV-2 virus could reach 1.02 × 104 copies/mL.•A dual-functional platform for rapid and sensitive detection of SARS-CoV-2 spike 1 protein in the field was established. The proposed LFIA system could be applied to detect other pathogens.