In order to evaluate the relationship between the photochemical reflectance index (PRI) and xanthophyll cycle, the diurnal variations of spectral reflectance at leaf or canopy level, actual photochemical efficiency of PSⅡ（ΦPSⅡ）, non-photochemical quenching (NPQ) in two field-grown species (Salvia splendens Ker-Gawl., Trifolium repens Linn.) were analysed, the leaves sampled for reflectance were subsequently harvested to assay xanthophyll cycle pigment content by high-performance liquid chromatography (HPLC). The results showed that the photochemical reflectance index (PRI) measured at leaf or canopy level was negatively correlated with de-epoxidation status of total xanthophyllpigment pool size((A+Z)/( A+Z+V)) and non-photochemical quenching (NPQ). The actual photochemical efficiency of PSⅡ (ΦPSⅡ) was positively correlated with the PRI. The results demonstrated that the PRI measured at leaf level or canopy level was a good indicator of light use efficiency in photosynthetic apparatus.