In recent years, underwater Internet of Things and marine Internet of Things have become a hot research direction. As an important part of marine Internet of Things, the routing protocol of underwater acoustic sensor networks has also received extensive attention from researchers. Therefore, based on HH-VBF(hop-by-hop vector-based forwarding) protocol, this paper proposed an energy-saving routing protocol for underwater acoustic sensor networks called ES-HH-VBF(energy-saving hop-by-hop vector-based forwarding) protocol. ES-HH-VBF protocol kept the location information of the next hop node as the reference value for calculating the node forwarding factor, and introduced the remaining energy of the node to improve the calculation method of the node forwarding factor, so as to balance the energy consumption in the network. And this paper also changed the preset distance threshold from the fixed value in HH-VBF protocol to the dynamic value based on the change of node residual energy, thereby dynamically controlling data redundancy. In order to verify the performance of ES-HH-VBF protocol, this paper compared and analyzed the performance of HH-VBF protocol and ES-HH-VBF protocol on the underwater sensor network simulator Aqua-Sim. The simulation results show that, with the increase of packet transmission interval between nodes, the packet delivery rate of ES-HH-VBF protocol is about 4.2% higher than that of HH-VBF protocol, the average network delay is about 11.3% lower than that of HH-VBF protocol, and the ave-rage network energy consumption is about 8.2% lower than that of HH-VBF protocol. Through the simulation analysis of ES-HH-VBF protocol and HH-VBF protocol, it shows that ES-HH-VBF protocol has great advantages in improving packet delivery rate, reducing average energy consumption and average delay.