Early cancer screening is essential for reducing cancer-related mortality and improving survival rates. Simultaneous detection of multiple tumor markers can enhance the accuracy and specificity of cancer diagnosis, helping us to mitigate false-positive results associated with single-marker analysis. Here, we have developed a lateral flow detection platform that combines recombinase polymerase amplification (RPA), CRISPR Cas9, and catalyzed hairpin assembly (CHA) for the simultaneous detection of KRAS ctDNA and miRNA-223 in lung cancer. The CRISPR Cas9 system acts as a linking element, enabling specific recognition and binding to RPA amplicons of KRAS ctDNA while facilitating the capture of Au-DNA-Bio nanoparticles (NPs), thereby producing a stronger detection signal through Au NPs aggregation. The CHA system enhances this platform by providing sensitive detection of miRNA-223. Our platform was tested on a limited number of clinical saliva samples, demonstrating feasibility but requiring further validation with larger cohorts.