The invention provides a preparation method for a binder-free NiO/Ni cathode of a sodium-ion battery. The method specifically comprises the following steps of cutting nickel foam to 4*3.5cm, utilizing hydrochloric acid to soak in order to remove an oxide layer and then utilizing ammonium hydroxide to carry out soaking treatment; placing multiple pieces of treated nickel foam into a container, adding deionized water to 50% of the volume of the container, continuously ventilating in a water bath kettle at 70-90 DEG C to react for 8-16 hours, after the reacted foam nickel is cooled to room temperature, utilizing an appropriate amount of ethanol to ultrasonically wash for 30-60 seconds by, and then drying in a blast oven at 60 DEG C; and sintering the dried foam nickel in the atmosphere of air or nitrogen at 250-350 DEG C for 5-12 hours and cooling to the room temperature to obtain a NiO/Ni sample. According to the method, the material is applied to the cathode of the sodium-ion battery, the better electrochemical performance is shown, and the material has good research prospect when being taken as the anode material of the sodium-ion battery.