The mechanical properties and environmental embrittlement of ordered (Fe,Co)3V alloys doping with various boron content have been investigated when tensile tested in vacuum and 1 kPa H2. The results show that the grain size of the ordered (Fe,Co)3V alloy doped with 0.02 wt.%B decreased by 27.5 % compared with boron-free (Fe,Co)3V alloy, while the tensile strength and elongation reached the maximum. However, as the boron content in the ordered (Fe,Co)3V alloy exceeds 0.02 wt.%, the grain size and mechanical properties remain unchanged when tensile tested in vacuum and hydrogen gas. The ordered boron-free (Fe,Co)3V alloy exhibits severe brittleness in hydrogen gas. By adding 0.02 wt. %B the hydrogen embrittlement factor of the ordered (Fe,Co)3V alloy decrease by 34.4 % and the fracture mode changes from full intergranular to mixed fracture of intergranular and transgranular. But when boron content increases continuously in the ordered (Fe,Co)3V alloy, the hydrogen embrittlement factor keeps about 50 %, indicating boron cannot completely suppress the environmental embrittlement of the ordered (Fe,Co)3V alloy in hydrogen.