Bidirectional Label Switch Paths (LSPs) are important parts of Multi-Protocol Label Switching- Transport Profile (MPLS-TP) networking technology. However, the existing algorithms of establishing bidirectional LSPs have redundancy in operation, control overhead, and waiting time of data packets. To address this problem, a novel algorithm based on single trips of control packets, Efficient Algorithm for Establishing Biderictional LSPs (EAEBL), is proposed in this article. On the premise of completing the establishment of bidirectional LSPs, EAEBL only needs to transfer the control packet through a single trip, thus the redundancy in operation and control overhead is reduced and conveying data packets is accelerated. Theoretical analysis verifies the effectiveness of EAEBL. Simulation results show that EAEBL reduces the control overhead and delay for establishing bidirectional LSPs by at least 14.7% and 50%, respectively, as compared with three existing algorithms. Moreover, the waiting time of data packets in source LSPs is decreased to approach zero.