Reservoir modifying method through forming crack network by temporary plugging turning in cracks

The invention provides a reservoir modifying method through forming a crack network by temporary plugging turning in cracks. The method comprises the following steps: injecting a temporary plugging turning material liquid into a reservoir man-made crack and forming a bridge plug in the deep part of the crack, forcing the crack to turn and form a plurality of cracks, using an active fluid or an acid fluid to activate reservoir micro-cracks, and forming the crack network. The method can form the man-made crack network in unconventional oil-gas reservoirs such as low-permeability, ultra low permeability oil-gas reservoirs, tight oil reservoirs and shale oil-gas reservoirs, so as to increase the contact area to the reservoirs and greatly shorten the seepage distance and the seepage resistance of the oil and gas in the reservoirs towards the cracks in the arbitrary directions, and furthermore the single well yield and the final recovery efficiency are increased.