In order to save cement resources and respond to the goal of “double carbon”, the use of industrial solid waste red mud and steel slag powder combined with cement to solidified fluid soil were explored. The working performance, compressive strength, electrochemical impedance spectroscopy and microstructure of the fluidized solidified soil with different red mud and steel slag powder content were investigated. The results show that the working performance of fluidized solidified soil can be regulated by changing the red mud and steel slag powder content. The slump increases first and then decreases with the increase of red mud content, when the red mud content is 10% (mass fraction), the slump reaches the maximum value of 203.0 mm. The setting and hardening time decreases with the increase of red mud content, the initial setting time ranges from 250 to 285 min. The compressive strength of fluidized solidified soil is mainly composed of hydrate calcium silicate (C-S-H) gel and ettringite generated by hydration reaction. At the age of 28 d, the compressive strength reaches the maximum value of 4.67 MPa, when the red mud content is 20% (mass fraction). There is a synergistic effect between red mud and steel slag powder, the addition of red mud and steel slag powder increases the production of C-S-H gel, and improves the mechanical properties of fluidized solidified soil. With the increase of red mud content, the arc radius of capacitive reactance, impedance modulus and phase angle peak, pore solution resistance Re and double electric layer capacitance Q all increase first and then decrease, and they all reach the maximum value when the mass ratio of red mud, steel slag powder and cement is 2∶3∶5. The results of electrochemical impedance spectrum and its equivalent circuit fitting are consistent with the variation law of compressive strength, electrochemical impedance spectrum technology is feasible in non-destructive testing of curing effect of fluidized solidified soil.