Abstract: The agronomic traits and leaf physiological changes of different leaf-color of Amaranthus tricolor in early spring were studied by semi-open field shade treatment，to provid the experimental basis for screening of resistant A. tricolor varieties and their scale production. The results showed that: the plant height and plant crown diameter increased，dry matter accumulation and root/shoot ratio decreased after 14 days of field shade. The Chlorophyll and carotenoids significantly decreased. Chl a decreased less than Chl b，and Chla/Chlb ratio increased. The degree of declining of total antioxidant capacity was ‘Green round leaf’ type（ YL）> Taiwan‘ Red leaf’ type （TH） >‘ Green sharp leaf’ type（ JL）> Alishan‘ Red leaf’ type（ AH）. The amaranthine of‘ Red leaf’ types of A. tricolor showed a tendency to decrease first and then rose，and the kAma / Chl increased significantly，revealing that the pigment is different from the mechanisms of low light physiological regulation of anthocyanin. Different leaf-color types of A. tricolor had different responses to weak light stress，field shade inhibited TH leaf number and its growth， but‘ Red flower’ type（ AH）of A. tricolor had good adaptability to weak light environment，its leaf area increased by 14.6%-26.7% at later stages，and its amaranthine content increased significantly. The shade tolerance of four tested amaranth cultivars was: AH> YL> JY> TH. TH and JL were suitable for full-light condition growth；Combined with the yield and plant quality of AH and YL，Alishan‘ Red leaf’ type（ AH） is more suitable for cultivation in early spring field in the Pearl River Delta region of Guangdong Province.