Metasurface provides an excellent platform for optical sensing, enabling enhanced light-matter interactions by controlling optical response in the desired manner. Herein, we introduce a metasurface biosensor incorporating a periodic array of split-ring resonators (SRRs) to achieve a Bound States in the Continuum (BIC) mode by introducing a slight asymmetry in the SRRs design. To enhance the trace detection capabilities of biosensor, the CD97 antibody is conjugated with 40nm gold nanoparticles (AuNPs). By capitalizing on the superior sensitivity of metasurfaces and the high refractive index of AuNPs, the research successfully demonstrates accurate quantitative detection of the gastric cancer-specific transmembrane protein CD97, with spectra dynamic response to concentrations spanning from 1 pM to 100 nM. This work paves a new way into metasurface design and has the potential to build a new method for early diagnosis of cancer through the specific transmembrane proteins.