We propose and study an innovative magnetic sensor of incomplete surface defect one-dimensional (1D) photonic crystal composed of magnetic fluid, SiO₂, and TiO₂ as defect layers. The magnetic fluid film covers the surface of the 1D photonic crystal, whereas the magnetic fluid penetrates into the array of circular holes with period ∧ inscribed on the dielectric layers of SiO₂ and TiO₂ to form the incomplete surface defect layer. The sensing characteristics of a 1D photonic crystal magnetic sensor (1D-PCMS) were analyzed using the theory of rigorous coupled wave analysis. The innovative use of the angular interrogation method in magnetic field detection has investigated the effect of defect layer structure parameters, optical dielectric loss on magnetic sensor sensitivity and quality factor at a fixed wavelength. This incomplete surface defect mode 1D-PCMS structure demonstrates the feasibility of scanning angular measurements of magnetic fields and provides a reference for future research on 1D-PCMS based on angular interrogation.