To enhance the flame retardancy and degradability of epoxy resin, vanillin-based epoxy monomer (Van-EP) was synthesized using vanillin as the primary raw material. Additionally, hexa(4-acetylphenoxy)cyclotriphosphazene (HACP) was synthesized from the flame-retardant unit hexachlorocyclotriphosphazene to serve as flame retardant and curing agent, thereby preparing a highly cross-linked, degradable, and flame-retardant vanillin-based epoxy resin. The curing behavior, thermal stability, degradability, mechanical properties, and flame retardancy of the vanillin-based degradable flame-retardant epoxy resin (HVEP) were systematically investigated. Non-isothermal differential scanning calorimetry (DSC) was employed to analyze the curing kinetics of HVEP. The curing kinetics parameters were obtained using the self-catalytic model, and it is found that the fitted curve is in good agreement with the experimental curve. The results indicate that the autocatalytic model can accurately describe the curing process within heating rates of 2.5~20 K/min. The optimal curing conditions was determined by extrapolation method as follows: 2 h at 120 °C followed by 2 h at 150 °C. The resulting HVEP resin exhibits a flexural strength of 153 MPa and an impact strength of 2.74 kJ/m2. The HVEP resin demonstrates comparable thermal stability to commercial epoxy resin (EP). However, it achieves a significantly higher char yield of 48.4% at 1000 °C. Furthermore, HVEP resin displays excellent flame retardancy with a limiting oxygen index (LOI) of 28.4% and achieves a UL-94 V-0 rating in the vertical burning test. In addition, the HVEP resin displayd relatively good degradability, with a degradation rate reaching 0.29 mg/(mL·h) in a 0.2 mol/L HCl solution (V(THF)/V(H?O) = 8/2).The results indicate that the molecular chain of HVEP contains both cyclotriphosphazene and Schiff base structural units, which contribute to its flame retardancy. The Schiff base structure also imparts degradability, enabling HVEP to exhibit balanced mechanical, flame-retardant, and degradable properties. These findings are of significant importance for broadening its application fields.