Abstract: Shading is a key cultivation technique in cigar tobacco production. A laboratory experiment was carried out to clarify the effect of low light on leaf morphological structure and its physio-biochemical characteristics. The different light intensities were set as higher T200200±15 μmol/(m²·s), middle T100100±15 μmol/(m²·s), and lower T5050±15 μmol/(m²·s) using cigar cultivar H382. The effects of different light intensities on the morphological characteristics, leaf structure, and endogenous hormone contents were studied. The results revealed an increment in leaf length, leaf width, leaf area, and specific leaf area while a reduction was witnessed in single leaf dry mass and specific leaf weight as light intensity decreased. Similarly, the chlorophyll content was also decreased under low light intensity. Additionally, the size of the upper and lower epidermis and palisade tissues was decreased. The size of spongy tissues was also decreased in the order T100 < T50 < T200 with larger intercellular spaces. Finally, the auxin (IAA) and abscisic acid (ABA) contents in the leaf were significantly reduced, gibberellin (GA₃) content was increased while Zeatin (Zt) was firstly increased and then dcereased under low intensities. Our results uncovered two different effects of various light intensities on a cigar tobacco leaf. One was, as it improved GA₃ content, reduced ABA content, and promoted leaf development via higher leaf area. The second effect was a decrease in the IAA content, leaf tissue thickness, chlorophyll content, and dry matter accumulation.