The invention relates to the field of petroleum engineering hydraulic fracturing, in particular to shear thickening liquid and a modified degradable fiber based thereon, a preparation method and a temporary blocking deflection fracturing method. The temporary blocking deflection fracturing method comprises: step 1, preparing the shear thickening liquid; step 2, modifying the degradable fiber DF-1;step 3, setting a fracturing packer and injecting prepad fluid to press and open a stratum; step 4, inject sand-carrying fluid mixed with the modified degradable fiber to fill a crack; step 5, injecting a fiber deflection agent solution for deflection and fracture forming; step 6, filling a new fracture with the sand-carrying liquid mixed with the modified degradable fiber, and then replacing forstopping pumping. A non-Newtonian fluid is utilized to modify the degradable fiber DF-1, so that a net structure formed by the fiber in the solution is more stable, and the temporary blocking abilityof the stratum crack is greatly enhanced; compared with the prior art, more deep branch seams can be formed, thus greatly improving the communication between old seams as well as natural cracks and unused reservoir areas, and achieving the suitability for popularization and application in low-permeability tight reservoirs.