A glass bead consisted of the β − -emitting 142 Pr is proposed for brachytherapy treatment of prostate cancer. Appropriate radionuclide and seed dimensions were selected and sample seeds were manufactured. For the quantitative dosimetric parameters, two-dimensional dose distributions were calculated using the MCNP5 Monte Carlo code and measured using radiochromic film. The computational results compared well with measurements. Dose at 0.6cm from the seed center can exceed 130Gy. The reference dose rate, radial dose function and the anisotropy function were derived.