We report a compact single-mode multi-trench fiber（MTF） with 40 μm core diameter and 10 cm in length based on the Nd-doped silicate glass.Both delocalization effect and the leaky nature were considered together to design the MTF. The fiber was fabricated by using the rod-in-tube method according to the design. A maximum laser output power of ～8.4 W with a slope efficiency of 54% was obtained from a 10 cm long singlemode MTF.