The invention provides a high-flowability rotational moulding polyethylene mixture and a preparation method of the high-flowability rotational moulding polyethylene mixture. The high-flowability rotational moulding polyethylene mixture comprises the raw materials of metallocene linear low density polyethylene (m-LLDPE), a metallocene ethylene-butene copolymer (m-EDC), linear low density polyethylene (LLDPE), a functional master batch, an antistatic agent, antioxygen, a coupling agent and a plasticizer. Therefore, the melt flowability is improved, and the high-flowability rotational moulding polyethylene mixture has the characteristics that a complex urea box product is easy to form and the antistatic performance is high.