Transmission housing pouring method and sand casting mould used in transmission housing pouring method

The invention relates to a transmission housing pouring method. The transmission housing pouring method comprises the following steps of: firstly, casting molten aluminum at 650-750 DEG C in a mould for 13-17 seconds; secondly, demoulding; thirdly, trimming; fourthly, heating a transmission housing after the trimming is finished to 515-535 DEG C from normal temperature for 2-4 hours, and keeping the temperature for 3-5 hours after the heating is finished; fifthly, taking out the transmission housing after the heat preservation is finished and quenching till room temperature, wherein the quenching medium is water, and the quenching lasts 10-15 minutes; and sixthly, secondarily heating the transmission housing after the quenching is finished to 160-180 DEG C from normal temperature and then keeping the temperature, wherein the heat preservation lasts for 2-3 hours.