This study determined the color change and the physical properties of extruded tea leaf-plastic composite (TPC) after accelerated weathering. The physical properties in TPC were studied using near infrared (NIR) spectroscopy. TPC experienced both change in color and loss of mechanical properties after weathering. The surface characteristics of TPCs also changed significantly after weathering. Exposure of TPC surfaces to weathering resulted in darkening of the color. The average board density (D), modulus of elasticity (MOE) and the modulus of rupture (MOR), for TPCs without weathering, were significantly larger than those for TPCs with different degrees of weathering. The majority of D, MOE and MOR changes occurred during the first 500 hours. The normalised difference vegetation index (NDVI) for TPC without weathering was significantly higher than samples with different durations of weathering. However, there was no significant difference between the values for different exposure times. The NDVI was the most important factor in determining D or MOE. Both the NDVI and the normalised difference lignin index (NDLI) values were used to predict D, using multiple linear regression. The results showed that NIR spectroscopy could potentially be used to determine the properties of tea leaf-plastic composites.