Abstract: Sorghum is an important food, feed and biofuel crop with ‘‘C4’’ photosynthesis. Understanding the mechanisms of sorghum growth and development regulated by light can help in molecular breeding to improve quality and better reveal the biochemical and morphological specifications. The present study used a Chinese home-made reversal satellite system to investigate blue light (BL)-mediated de-etiolation in the sorghum har1 mutant. The seeds of both the wild-type R111 and har1 mutant were germinated and pre-cultured under 1.8 mmol.m-2.s-1 far-red light for 6 h, then irradiated with BL under 12-h light (20 mmol.m-2.s-1)/12-h dark conditions. The young seedlings of har1 showed shorter coleoptiles and mesocotyls and inhibited grow th than the wild type 2 to 3 d after BL irradiation. Elongation of the leaf sheath was inhibited as well. The first and second leaf sheaths showed 25% to 48% inhibition in length as compared with that of R111, but leaf blades had similar lengths. Moreover, the anthocyanin accumulation in mesocotyls of 3-d-old har1 seedlings was remarkably higher than that of R111 after continuous BL irradiation; red and farred light had no significant effect on pigmentation. Plastids developed in 3-d-old har1 leaves during de-etiolation, with more developed grana. The content of chlorophy ll in har1 seedlings was higher than that of R111 seedlings after 24-h BL irradiation. Immunoblot analysis with anti-SbCRY1b antibody showed SbCRY1b expressed in both R111 and har1 mesocotyls of 7-d-old seedlings grown under 12-h BL/12-h dark. Seedlings of the har1 mutant showed higher accumulation of SbCRY1b in darkness. Our results suggest that har1 is hypersensitive to BL during de-etiolation. The role of SbCRY1b in the BL-mediated response of har1 remains to be elucidated.