The invention provides a container sheet material and a preparation method thereof, and relates to the field of basalt fibers. The preparation method of the container sheet material comprises the following steps: mixing first resin with a curing agent to obtain a resin pool; paving cloth in the resin pool, scattering basalt fibers in the resin pool to distribute basalt fibers on the cloth, spraying second resin on the basalt fibers, covering a film on the second resin, and carrying out press roll extrusion, heating, and moulding. The skeleton material of the container sheet material is basalt fibers, and thus the container sheet material has the characteristics of basalt fibers such as good flame retardant performance, excellent corrosion resistant performance, lightness, and the like and has a high mechanical strength at the same time.