Transversity is quark's transverse polarization in a transversely polarized nucleon. At a realistic 3-D point of view, out of three leading order quark distributions, transversity is the lease known one. At Jefferson Lab Hall A, we recently finished the first measurement of the neutron target single spin asymmetry in the semi-inclusive deep inelastic scattering with a transversely polarized ³He target. The goal is to extract neutron transversity which gives a unique azimuthal angular dependence in target single spin asymmetry when convoluted with Collins fragmentation function in SIDIS reactions. Other two leading twist transverse momentum distributions, Sivers function and pretzelosity, will be extracted as well. The data from this experiment, when combined with world data collected on proton, deuteron SIDIS and e⁺e^- annihilation, will provide constraints on the transversity and Sivers distributions on both u-quark and d-quark in the valence region.