Experimental research on the shear test behavior of different shear-span ratios and different stress modes was carried out through the experimental research on two general beams and four RC beams strengthened with steel fiber ferrocement mortar. The regulation for the change of the mode of failure, diagonal cracks, deflection and strain was analyzed in the experiment. According to the test results, the computational formula of the shear load capacity of RC beams strengthened with the steel fiber ferrocement mortar was established. The calculation results fit well with the experimental results, which provides a theoretical reference for actual engineering designs.