The molecular dynamics (MD) simulation employing a Tersoff potential was performed to examine the nanomechanical behavior of the beta-SiC nanowire in tension. The elongation was much larger than that of the bulk beta-SiC. We observed non-homogeneous deformation, and the fracture behavior was found to depend on size, orientation and temperature of the specimen. The Young's modulus calculated in this study generally decreased with temperatures and increased with the radius, namely, the diameter of the beta-SiC nanowire as long as the length scale remained the same. The initial orientation was found to have a more serious effect on the Young's modulus than size and temperature. The [1 1 1] Young's modulus is much higher than that of the  orientation. The fracture of the beta-SiC nanowire in the  orientation showed two different modes, which is brittle at 100 K and ductile at 300 and 500 K. The ductile fracture was accompanied by formation of an atomic chain. In the [1 1 1] orientation, it was always fractured in the ductile mode and thus an atomic chain was formed before rupture.