Abstract: This study investigates the influence of temperature and stress levels on the creep behavior of glass fiber reinforced plastics (GFRP) composite materials in deionized water environment. After treating the specimens with resin edge sealing, long-term creep tests were conducted at 20%, 30%, 40%, 50%, and 60% stress levels under 20℃, 30℃, 40℃, 50℃, and 60℃ conditions using a constant load bending corrosion test machine. Furthermore, long-term creep tests were also performed at 20%, 30%, 40%, and 50% stress levels under 30℃ conditions. The study separately examines the effects of different temperatures and stress levels on the creep performance of GFRP, quantifies the comprehensive impact of temperature and stress levels on the creep behavior of GFRP in deionized water environment, and establishes an improved Findley nonlinear creep model. Additionally, the study assesses the influence of deionized water environment on the interlaminar shear strength of GFRP using the short beam shear method. The results indicate that the improved Findley nonlinear creep model can accurately describe the creep performance of GFRP at temperatures ranging from 20℃ to 60℃ and below its creep fracture stress level, showing a broad applicability and high accuracy with good agreement with experimental results. Based on this model, the long-term creep performance of GFRP composite materials under different temperatures and stress levels in deionized water environment can be predicted, with prediction errors within 2%. Deionized water has minimal impact on the interlaminar shear strength of edge-sealed GFRP specimens. The findings of this study provide a basis for the design of GFRP structures.