We developed a colorimetric sensor array with reported protein aptamers as nonspecific receptors. We found that different target proteins could make the aptamer-protected gold nanoparticles (AuNPs) exhibit different aggregation behaviors in the presence of a high concentration salt and cause various color change. On the basis of this phenomenon, we applied a series of reported protein aptamers as a receptor array obtaining a distinct response pattern to each target protein. Seven proteins have been well distinguished with the naked eye at the 50 nM level. Cancerous human cells have also been discriminated from noncancerous cells. This method is simple, label-free, and sensitive. It will broaden the application filed of plasmonic nanoparticle-based sensors and give a new direction of developing sensitive array sensing systems.