The weightlessness environment produced in space flight will affect a series of life processes of plants. Therefore, in order to ensure the normal growth of plants, it is very important to reveal the growth and development law of plants under weightlessness environment. In this study, the seedlings of Arabidopsis thaliana were treated in a simulated weightlessness environment by using the diamagnetic levitation generated by a superconducting magnet with Large Gradient High Magnetic Fields. After 4 days of cultivation, the growth and development of hypocotyl cells and the arrangement of cortical microtubules in Arabidopsis thaliana under different gravity conditions were recorded, and image quantitative analysis and statistical analysis were carried out. The results showed that, compared with control group, gravity change had different effects on seedling morphology, plant height, hypocotyl cell morphology and arrangement of cortical microtubules. Especially in the case of simulated weightlessness (μ g), seedling bending was obvious, plant height was significantly lower than other groups, cell length-width ratio was smaller, and hypocotyl cortical microtubules were rearranged. The comparison among control group, 1 g group and 2 g group (simulated hypergravity) showed that there were no significant differences in other indicators except for the arrangement of microtubules. The results suggest that simulated weightlessness has a significant effect on plant growth and development, and microtubules are involved in the sensing and transduction of gravity signals. It is speculated that microtubules may regulate hypocotyl growth through its rearrangement, and participate in the inhibition of hypocotyl elongation by simulated weightlessness to affect plant morphogenesis.