An iron（Ⅱ） formate [H3CO3][Fe（HCO2）3] （1） has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction analysis. Complex 1 crystallizes in the orthorhombic system, space group Pnna with a = 8.4130（4）, b = 11.8306（6）, c = 8.9468（4）A, a = 106.527（4）, β = 105.876（4）, 7 = 103.173（4）°, Mr= 253.94, V= 890.48（7） A3, Z= 4, Dc = 1.894 g/cm3,μ = 1.721 mm^-1, F（000） = 512, Rint = 0.0164, the final R = 0.0323 and wR = 0.0998 for 979 observed reflections （I 〉 2σ（I））. 1 exhibits a 3D open microporous framework formed by formate anions bridging Fe（Ⅱ） ions.
