Abstract: Experimental tests on three-point bending fracture of steel fiber and nano-particle reinforced concrete is conducted to study the effect of nano-particles, steel fibers and relative notch depth on its fracture toughness, focusing on the measurements of fracture energy and fracture process. The test results indicate that adding appropriate contents of nano-SiO2 and steel fibers to the concrete can improve its fracture energy significantly. As the nano-SiO2 content is increasing, fracture energy is increased gradually up to a peak content of 5% and then decreased gradually. And with the increasing steel fiber content, it manifests a similar tendency and has a peak value at the content of 2%. The depth of a relative notch on a beam specimen has great effect on its fracture energy that is decreased gradually with the increasing depth.