To achieve precise discrimination and measurement of dielectric properties for multi-form materials, this study proposes a microwave planar sensor based on a complementary split-ring resonator-defected ground structure (CSRR-DGS), whose unique configuration significantly enhances localized electric field intensity, resulting in a 51.1% improvement in quality factor compared to conventional planar structures, enabling accurate measurements for both solid and liquid dielectrics. Simulation results demonstrate that when testing 4 mm×4 mm×1 mm cubic samples with relative permittivity ranging from 1 to 15, the sensor exhibits excellent linear response characteristics in resonant frequency, which was experimentally validated through measurements of polytetrafluoroethylene (PTFE), 3240 epoxy board, FR4 fiberglass laminate, and acrylonitrile-butadiene-styrene (ABS) resin, showing strong agreement with simulation data and yielding an average relative error of 2.4% for solid dielectric measurements based on the established mathematical model. Furthermore, characterization of ethanol solutions with varying concentrations established a reliable correlation between solution concentration and relative frequency shift, achieving an average relative error of 4.6% for liquid dielectric measurements, collectively demonstrating the sensor′s outstanding performance in dielectric characterization and its effectiveness as a high-precision solution for multi-form material detection.