We proposed a trench-nanopore assisted double-clad weakly coupled few-mode fiber to alleviate the crosstalk caused by the coupling of adjacent linearly polarized (LP) modes. First, the finite element method was employed to analyze the effects of the fiber parameters on the minimum effective refractive index difference (Δn_eff) between adjacent LP modes. Then, the fiber was optimized to support 14 LP modes and satisfy the weak coupling conditions. Finally, we analyzed the bending loss, effective mode field area, and differential mode group delay of the optical fiber. Simulation results show that a minimum Δn_eff of larger than 6×10 ^-4 among all LP modes over the C+L band can be achieved by introducing a nanopore with a 253 nm radius in the center of the fiber core. Meanwhile, the trench assistance structure added reduces the bending loss from 10 ^-3 dB/m to 10 ^-5 dB/m, thereby providing the fiber with favorable bending resistance. The fiber, with good transmission performance, has great application potential in short-distance large-capacity mode division multiplexing systems.