In order to explore the impact of temperature and humidity variations on self-sensing concrete (SSC) efficacy, the functional group of carbon nanotube(CNT) was performed by the low-temperature plasma modification to enhance the dispersion in aqueous systems. The resulting modified carbon nanotubes (P-CNT) were integrated into the concrete to form P-CNT/SSC sensors. Varying water content and temperature conditions were tested to assess the polarization effect of P-CNT/SSC sensor and SSC’s self-sensing capabilities under cyclic loading. Results show that too high or too low water content impaired SSC’s sensing abilities, with the most significant impact observed under full water conditions, leading to an 89.8% decrease in stress sensitivity coefficient and unstable pressure-sensitivity curves. Moreover, during temperature variation tests, P-CNT/SSC resistivity exhibited a negative correlation with temperature. Stress sensitivity coefficients decreased by approximately 35.66% and 44.53% at high and low temperatures, respectively, compared to room temperature specimens, and the pressure-sensitivity curves displayed upward shifts or downward slides. Thus, the study suggests that the optimal testing condition of P-CNT/SSC applications involves room temperature and natural moisture content.