As a wide-bandgap semiconductor,4H-SiC is an ideal material for high-power and high-frequency devices,and plays an increasingly important role in developing our country's future electric vehicles and 5G techniques.Practical applications of SiC-based devices largely depend on their mechanical performance and reliability at the micro-and nanoscales.In this paper,single-crystal[0001]-oriented 4H-SiC nanopillars with the diameter ranging from～200 to 700 nm were microfabricated and then characterized by in situ nanomechanical testing under SEM/TEM at room temperature.Loading-unloading compression tests were performed,and large,fully reversible elastic strain up to～6.2％was found in nanosized pillars.Brittle fracture still occurred when the max strain reached～7％,with corresponding compressive strength above 30 GPa,while in situ TEM observation showed few dislocations activated during compression along the[0001]direction.Besides robust microelectromechanical system(MEMS),flexible device and nanocomposite applications,the obtained large elasticity in[0001]-oriented 4H-SiC nanopillars can offer a fertile opportunity to modulate their electron mobility and bandgap structure by nanomechanical straining,the so called“elastic strain engineering”,for novel electronic and optoelectronic applications.