Weakly consolidated sandstone (WCS) is a common reservoir used in petroleum development. Owing to its loose structure, sand production and formation collapse frequently occur during oil and gas extraction, posing significant challenges in the petroleum industry. To address these issues, some researchers have proposed in-layer reinforcement sand control methods for weakly consolidated sandstones. To implement this approach, developing a permeability-self-restoring proppant (PSRP) for in-layer reinforcement is essential. The aim is to support the fractures created by fracturing, ensuring that the curable working fluid is not displaced and that the curable liquid does not infiltrate the voids of the PSRP, thereby preventing a substantial reduction in permeability. In this study, a new structure and principle for the PSRP are proposed. Polylactic acid (PLA) was selected as the filling material due to its alkaline solubility. The size and quantity of hollow microspheres were optimised based on the permeability of the consolidated body. The optimal microsphere size was determined to be 50–80 mesh, with an optimal dosage of 10%. Subsequently, the PSRP was developed and incorporated into a permeable curing liquid system prepared by other experts. The permeability of the obtained consolidated body was measured as 25.47 × 10−3 μm2 after 1 d and 22.46 × 10−3 μm2 after 7 d at 15 °C and 20 MPa. The compressive strength after 1 d was 6.88 MPa. Compared to conditions without PSRP addition, the permeability of the consolidated body increased by 35.12% after 1 d and by 134.47% after 7 d. This research lays the foundation for applying sand-control methods in in-layer reinforcement.