A green, rapid, simple and reliable procedure was developed for nitrite determination using silver-miangnanocomposites as colorimetric agents and camera phone as a detector. The crude water extracts of miang (Camelliasinensis var. assamica) were adopted as natural reagents in a rapid one-pot microwave synthesis of thenanocomposites. The extracts' phytochemical contents were studied and the synthesis conditions were optimized.The yielded nanocomposites were characterized by UV-vis and FT-IR spectroscopies, powder X-ray diffraction,transmission electron microscopy, selected area electron diffraction and thermogravimetry, and proved to be reliablecolorimetric agents and selective for nitrite. The underlying reactions were investigated. The linear calibration plotscould be established based on the ratiometric R/G parameters over 2.0-10 mg.L-1 nitrite concentration range withsatisfying detection limits (0.12-0.62 mg.L-1). In practice, the procedure was validated and applied with water andcommercialized meat samples. The long storage time of miang (>5 years) was also evaluated, manifesting viability andreliability in views of both the nanocomposites synthesis and the nitrite determination performance.