We perform level statistics of the Nilsson single-particle levels. The effects of the l2 and l ? s; s terms are discussed as well as their interplay with the deformations. The results show that when the l2 term is added to the harmonic oscillator potential, chaotic motion occurs. The strength ranges of the l2 term in which chaotic motion exists are related to the deformation of the harmonic oscillator potential. The calculations of the localization length in different bases demonstrate that it is the spherical or axial symmetries that gove the chaotic motion. The degree of chaoticity increases significantly with the l ? s; s term included.