Wireless sensor networks (WSNs) comprise an extensive array of spatially dispersed sensor nodes, interconnected through a wireless medium to monitor and record physical information from the environment. In WSNs, multi-hop routing is employed for data transmission among nodes, rendering these networks susceptible to a diverse range of attacks. In order to mitigate these threats, proficient trust management schemes must be employed to ascertain node reliability and segregate malevolent nodes from the rest of the network. In recent years, trust-based routing protocols and multipath routing have become important ways to improve the security and performance of WSNs. This paper mainly introduces grey theory based on multipath and proposes a low energy security-aware routing protocol for WSNs based on grey clustering analysis (SPBCDS). Firstly, during the route establishment phase, the protocol employs a grey clustering analysis algorithm to classify the security status of each candidate cluster by conducting security analysis of the cluster area. Secondly, to ensure data privacy and enhance protocol fault tolerance, a dynamic slicing technique is introduced to select the set of candidate cluster heads, taking into account both the security status of the candidate clusters and the distance between cluster heads. Subsequently, the packets are sliced proportionally based on the security status level of the candidate clusters and directed to the corresponding candidate cluster head nodes. Experimental results demonstrate that this algorithm effectively reduces network energy consumption, extends the network lifecycle, and enhances overall network reliability.