The invention relates to a sand grain removal system for motorcycle castings. The sand grain removal system comprises a base system. A material collection system is installed on the lower portion of the base system. A left supporting column is arranged at the left side of the upper portion of the base system, and a right supporting column is arranged at the right side of the upper portion of the base system. A left processing system is arranged at the right side of the left supporting column, and a right processing system is arranged at the left side of the right supporting column. Supporting frames are installed on the right side of the left processing system and the left side of the right processing system correspondingly. Cover plates are arranged on the upper portion of the left supporting column and the upper portion of the right supporting column through hinges correspondingly. A storage system is installed at the middle position of the lower portion of the right processing system. Discharge pipes are arranged on the left side of the lower portion of the left processing system and the right side of the lower portion of the right processing system correspondingly. A material outlet pipe is arranged on the lower portion of each discharge pipe. A draught fan system is installed at the middle position of the lower portion of the base system. By means of the system, the sand grain removal processing can be effectively conducted on casting products of the motorcycles, recycling of sand grains is facilitated, placement and purging sand removal are facilitated for the casting products of the motorcycles, dust removal can be conducted in time, and influences on the environment are avoided.