Abstract: To address the technical challenges of severe reservoir damage and high operational costs associated with conventional fracturing processes that rely on guar gum-based thickeners, a zwitterionic terpolymer was synthesized through molecular synergistic design. The surface of quartz sand substrate was modified using an integrated coating process combining constant-temperature coating with in-situ crosslinking and curing, which resulted in a molecularly modified self-suspending proppant capable of self-suspension in fresh water. Laboratory evaluation results demonstrated that the proppant achieved roundness and sphericity of 0.9, a crushing rate of only 2.07% under a closure pressure of 35 MPa, temperature resistance up to 110 ℃, and adaptability to environments with high salinity as high as 20×10⁴ mg/L. Under conditions of 70 ℃ and an 8% proppant concentration, complete self-suspension was achieved within 55 s, with no solid-phase sedimentation observed within 150 min. The fracture conductivity under 50 MPa closure pressure reached 26 D·cm, which was twice that of uncoated quartz sand, and the residual mass concentration after gel breaking was below 50 mg/L. Field tests were conducted in 9 low-permeability tight gas wells in Block S, employing a composite fracturing technique of “pad fluid for inducing fractures + self-suspending sand-carrying by fresh water”. No thickener was added during the sand-carrying stage, and a 100% operational success rate was achieved with an average flowback rate of 75.2% and a maximum open flow of 10.11×10⁴ m³/d for a single well. In comparison with conventional guar gum fracturing in the same reservoir, the average production increase reached 112.5%. This study confirms that the molecularly modified self-suspending proppant enables thickener-free sand-carrying fracturing by fresh water, which effectively reduces reservoir damage and lowers operational costs, thereby providing a novel technical approach for efficient fracturing stimulation in low-permeability tight gas reservoirs.