To effectively address the issue of spectrum fragmentation resulting from resource allocation in space division multiplexing elastic optical networks (SDM-EON) of multi-core fiber, a load resource synergy temporal-spatio-frequency (LRS-TSF) fragmentation perception algorithm was proposed. Firstly, a routing selection strategy was designed by considering the path load and service frequency slot requirements, prioritizing paths with lower path load and fewer service frequency slot demands. Then, a 3-D measurement of available spectrum resources was conducted from the perspective of time, space, and frequency, introducing a TSF fragmentation perception model to avoid spectrum fragmentation during the service allocation process and reserve contiguous idle spectrum resources for subsequent services. Simulation results demonstrate that when the load ranges from 400 Erlang to 960 Erlang, the LRS-TSF algorithm achieves better performance in terms of blocking probability, spectrum utilization, and fragmentation rate compared to other algorithms. The study provides a reference for further addressing the issue of spectrum fragmentation in elastic optical networks with spatial division multiplexing.