Abstract: PrCl_3-NaCl-LiCl phase diagram has been constructed from the phase diagrams of its sub-binary systems and of six quasi-binary systems measured by DTA technique.It is found that this ternary system is composed of five liquidus surfaces,seven second crystallization lines,two peritectic points and one eutectie point.The temperatures and compositions of invariant points are as follows:P_1(416℃,30.3 mol% NaCl,44.2 mol% LiCl,25.5 mol% PrCl_3);P_2(409℃,25.0 mol% NaCl,50.0 mol% LiCl,25.0 mol% PrCl_3);E(404℃,20.0 mol% NaCl,55.4 mol% LiCl,24.6 mol% PrCl_3).

Key words: PrCl_3-NaCl-LiCl, phase diagram, molten salt