This research work designed a novel mud-cake solidification method to improve zonal isolation of oil and gas wells. The calculation methodology of mud-cake compressive strength was proposed. The optimal formula of activator and solid precursors, the proper activating time and the best activator concentration were selected by compressive strength test. The effects of solid precursors on the properties of drilling fluid were evaluated. The performances of this novel method were measured. Test results show that the respective percentage of bentonite, metakaolin, slag and activator is 1:1:0.3:0.8, as well as the optimum ratio of Na2SiO3/NaOH is 40:1. The optimum concentration of activator is 0.21 due to the limited proportion of solid precursors in mud-cake, and the activating time should not lower than 10 min. The solid precursors did not show bad influence on the rheological property of drilling fluids in different conditions. Even though the compressive strength decreased when the solid precursors blend with barite or other drilling fluid additives, the strength values can still achieve 8 MPa. The reaction of metakaolin and activator formed crosslink structure in the mud-cake matrix, which enhanced the connection of the loose bentonite particles, lead to the significant enhancement of shear bonding strength and hydraulic bonding strength. This mud-cake solidification method provides a new approach to improve the quality of zonal isolation.