The invention discloses a method for slight fracture supporting, capable of increasing a fracture stabilization period. The method comprises the steps of (1) evaluation of a
microstructure of reservoir rocks, (2) a first-stage injection phase, and (3) second-stage and third-stage injection phases. During the second step, (1) an ultralow-
viscosity fracture solution carrying a micro-particle-
diameter supporting agent is injected to communicate and extend
natural fracture systems with micro scales, a low-
viscosity fracture solution carrying a small-particle-
diameter supporting agent is injected to communicate and extend
natural fracture systems with large scales; a middle-
viscosity fracture solution carrying a middle-particle-
diameter supporting agent is injected to extend fracture systems with large scales; and (4) a high-viscosity fracture solution carrying a large-particle-diameter supporting agent is injected to extend fracture systems with the maximum scale. According to the invention, through fine evaluation of the
microstructure of the reservoir rocks, alternate multi-stage injection, utilization of viscous fingering effects of various liquids with different viscosities, multi-scale sand adding and other methods, the fracture systems with the different scales within a full seam length scope of a main fracture can be fully expanded, extended and supported; and a "valid reshaping volume" of fractures and "supporting efficiency" of cracks are increased.