The indentation technique imposes high requirements on the accuracy of testing equipment in practical applications and is susceptible to disturbances from the testing environment and factors such as sample preparation quality. To optimize the key parameters of indentation experiments and enhance the reliability and scientific validity of this method, this study investigates the influence of experimental conditions on the indentation relaxation behavior of Sanicro25 austenitic heat-resistant steel using the finite element method. The simulation results indicate that the friction coefficient has an obvious impact on the test results. When the friction coefficient increases from 0 to 0.30, the corresponding maximum force increases by 18.41%. At the same time, the surface morphology of the indentation changes significantly. As the friction coefficient increases, the material stacking height decreases. However, when the friction coefficient exceeds 0.15, the change in stacking height becomes less pronounced, and the results under different friction coefficients tend to be consistent; the indentation response is also affected by the ratio of sample thickness to indentation depth (thickness-to-depth ratio). The results show that when the ratio is ≥ 20, the relaxation curves are essentially consistent. Further increasing the thickness-to-depth ratio does not lead to significant changes in the relaxation curve. Under the same indentation depth conditions, a quadrangular pyramid indenter produces a larger equivalent creep strain and a faster initial relaxation rate than a conical indenter.