Abstract： The crystal of 15-crown-5 nitrate praseodymium with composition Pr(NO3)3C10H20O5 belongs to monoclinic system. The space group is C2h5-P21/α with lattice parameters α = 13.622?, b = 14.599?, c = 9.336?, β = 95°20′ and 4 molecules in the unit cell. The intensities of 2853 independent reflection were collected by the PW-1100 four-circle diffractometer. The structure was solved by heavy-atom method and refined to a final R = 0.080 by block diagonal least square method. The praseodymium coordination comprises the five crown oxygens (Pr-Ocrown= 2.545?) and two oxygens from each of the three bidentate nitrates (Pr-O(NO3-)= 2.685?). The coordination number is eleven.