Introduction: Frailty assessment is crucial to the treatment of elderly patients with multiple myeloma. By frailty assessment, frail and non-frail populations can be distinguished to avoid insufficient or excessive treatment. Studies have confirmed that frailty is dynamically changing, and that dynamic frailty assessment is of a greater value in prognosis. However, there is no conclusion on the selection of the frailty assessment tools due to insufficient evidence. Among the assessment tools, IMWG-FI allows for dynamic assessment, but there are still some shortcomings. Methods: Fiftyeight newly diagnosed elderly patients with multiple myeloma who were ineligible for transplantation were included and underwent frailty assessment by gait speed, grip strength, IMWG-FI, IFM, and MRP at baseline and treatment courses 3 (C3) and 6 (C6), and the consistency of gait speed, grip strength, MRP and IFM with IMWG-FI was compared. Results: 1. The assessment consistency between MRP and IMWG-FI results was the best at baseline, with an AUC value of 0.795, followed by gait speed, with an AUC value of 0.785. In dynamic assessment, gait speed and IMWG-FI showed the best consistency, with an AUC value of 0.844. Further analysis showed that the consistency of gait speed grip strength and IMWG-FI increased at C3, with AUC values of 0.823 and 0.746, respectively. At C6, gait speed was equivalent to IMWG-FI with an AUC value of 1.0, followed by grip strength with an AUC value of 0.857. 2. Among frail patients with an IMWG-FI score of 2-5, under 80 years of age at C6 follow-up, frailty improvement was observed with dynamic improvements in gait speed but insignificant grip strength change in patients ; while in the patients over 80 years old, no change in IMWG-FI frailty was observed at C3 follow-up, but there was a significant improvement in gait speed and a insignificant improvement in grip strength. Conclusions: As a simple and feasible indicator for assessing frailty, gait speed was highly consistency with IMWG-FI in assessment results and showed greater advantages in dynamic assessment. In patients who cannot be dynamically assessed by IMWG-FI, the frailty state remains unchanged, while gait speed shows significant changes. The combination of gait speed and IMWG-FI can better improve the effectiveness of dynamic frailty assessment, identify patients who may be missed by IMWG-FI alone. This is worth for exploration especially for MM patients over 80 years old, where gait speed can be a highly potential dynamic frailty assessment indicator with grip strength as an effective supplementary