S2Cl2 is a candidate for the observation of ortho-para transition. To estimate the ortho para mixing in a hyperfine-resolved rotational state, pure rotational transitions were measured by millimeter-wave (mm-wave) spectroscopy using two different experimental set-ups., The transitions from the term value around 20 K was measured with a supersonic jet and those around 200 K were measured with a dry ice cooled gas cell. Several hundred peaks were assigned for the naturally abundant (S2Cl2)-Cl-35 and (S2ClCl)-Cl-35-Cl-37 isotopic species and the rotational molecular parameters including the fourth order and sixth order centrifugal distortion constants were determined The hyperfine structures were partly resolved in some Q-branch transitions, which were well described with the hyperfine constants determined by FTMW spectroscopy in the centimeter-wave region. With the new rotational constants determined in our study and the previous hyperfine constants, it will be possible to obtain a more reliable ortho para mixing ratio and to narrow down the possible candidate transitions in the mm wave region for the observation of ortho-para transition.