The Hanbit mirror device has been renovated as Multi-Purpose Plasma (MP2) facility for the divertor plasma simulation, space propulsion, and astrophysical researches. The intensity ratios of He I emission lines are used to determine electron density and temperature in MP2. The He I line ratios are measured by optical emission spectroscopy and are calculated using the collisional-radiative equilibrium model. The measured He I line ratios are 706.52 nm / 728.13 nm for electron temperature and 728.13 nm / 667.82 nm for electron density determination, respectively. The results obtained from the collisional-radiative equilibrium model are crosschecked with those of electrical probe measurement.