Powder laying is the key action of selective laser melting (SLM) process.The existing SLM forming equipment is mainly unidirectional powder laying,which takes a long idle time.A small number of equipment are equipped with bidirectional powder laying,but the structure is complex and the stability is poor.In order to solve the above problems,a singleknife bidirectional powder laying device was developed.In the device,the upper powder bin was used for powder supply,and the powder falling direction was controlled by the push plate.A large number of tests were carried out on the device.The results show that the bidirectional powder laying device has good stability,short idle time.At the same time,the convex or sharp edges existing on the forming surface can be cut off in the process of powder laying to ensure the flatness of the powder laying plane.By designing powder drop grooves with different widths,the device can meet the powder laying requirements of many kinds of powder and has wide range of applicability.