In order to further improve the recovery of imbibition fracturing fluid after well shut-in，the effects of different residue content and molecular weight of the thickener in fracturing fluid gel breaker on imbibition recovery were studied. Through the optimization of imbibition agent and its effects on the viscosity increasing，temperature resistance，shear resistance and imbibition recovery performance of non-crosslinked associative thickener（CFZ），a set of imbibition recovery non-crosslinked associative clean fracturing fluid system with low residue and low molecular weight was constructed and optimized. The results showed that the lower the residue content and molecular weight in gel breaker，the smaller the effect on imbibition recovery. When the system， composed of 0.3% thickener CFZ + 0.2% imbibition agent SZX-1 + 0.06% gel breaker APS，was sheared at the temperature of 90 ℃ and at the shear rate of 170 s^-1 for 90 min，the viscosity was 77.43 mPa·s. The contact angle of the gel breaker on oil wet surface was 31.6°，the oil-water interfacial tension was 0.66 mN/m，the residue content was 17.2 mg/L and the molecular weight of the thicker in the gel breaker was 1.15 × 10⁴ ，the imbibition recovery was 14.8%. The system provided the theoretical basis and technical support for further improving the imbibition recovery after fracturing.