Sentence ordering aims at restoring orders of shuffled sentences in a paragraph. Previous methods usually predict orders in a single direction, i.e., from head to tail. However, unidirectional prediction inevitably causes error accumulation, which restricts performance. In this article, we propose a bidirectional ordering method, which predicts orders in both head-to-tail and tail-to-head directions at the same time. In our bidirectional ordering method, two directions can interact with each other and help alleviate the error accumulation problem of ordering. Experiments demonstrate that our method can effectively improve performance of previous models.