Constrained translation has improved statistical machine translation (SMT) by combining it with translation memory (TM) at sentence-level. In this paper, we propose using a constrained word lattice, which encodes input phrases and TM constraints together, to combine SMT and TM at phrase-level. Experiments on English– Chinese and English–French show that our approach is significantly better than previous combination methods, including sentence-level constrained translation and a recent phrase-level combination.