The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials. To study the strength characteristics of loess soil reinforced by modified polypropylene (MPP) fiber and cement, samples were prepared with six different fiber contents, three different cement contents, three different curing periods and three kinds of fiber length. The samples were tested under submergence and non-submergence conditions for the unconfined compressive strength (UCS), the splitting tensile strength and the compressive resilient modulus. The results indicated that combined reinforcement by PP fiber and cement could significantly improve the early strength of loess to 3.65–5.99 MPa in three days. With an increase in cement content, the specimens exhibited brittle fracture. However, the addition of fibers gradually modified the mode of fracture from brittle to ductile to plastic. The optimal dosage of fiber to reinforce loess was in the range of 0.3%–0.45% and the optimum fiber length was 12 mm, for which the unconfined compressive strength and tensile strength reached their maxima. Based on the analysis of failure properties, cement-reinforced loess specimens were susceptible to brittle damage under pressure, and the effect of modified polypropylene fiber as the connecting bridge could help the specimens achieve a satisfactory level of ductility when under pressure.