Abstract: In response to the challenges of "undetectable and inaccurate monitoring" of cement sheath sealing integrity in oil and gas well cementing, this study proposes a multi-threshold coupled self-sensing cement slurry construction method. A self-sensing cement slurry system tailored to the demands of cementing engineering was developed, and its electrical response characteristics were systematically tested under cyclic loading conditions (30%–70% compressive strength). The system utilizes Grade G oil well cement as the matrix and incorporates an electrostatically self-assembled carbon nanotube/nanocarbon black (CNT/NCB) composite functional material, achieving a synergistic conductive effect that combines long-range and short-range conduction, significantly enhancing the conductivity and self-sensing capability of the cement slurry. The results indicate that this self-sensing cement slurry system has a transition time of 20 minutes, a flowability of 21 cm, a compressive strength of 54.5 MPa, and a strain sensitivity of 47. Its "mechanical-electrical" response capability is significantly superior to that of traditional cementing slurries, with the relative change rate of resistivity increased by sixfold. Furthermore, the changes in resistivity are highly synchronized with stress and strain, enabling real-time diagnosis of microcracks within the cement sheath through resistivity anomalies. This research provides theoretical support and a material foundation for the precise monitoring of cement sheath sealing integrity in complex oil and gas wells.