The invention relates to a grid forming method, which comprises the following steps of: providing a semi-conductor substrate, wherein, the semi-conductor substrate is formed a first oxidized silicon layer, a first polysilicon layer and an inter-level dielectrics layer; forming a second polysilicon layer on the semi-conductor substrate; removing the second polysilicon layer; forming the grid. Correspondingly, the invention further provides a forming method for high-voltage transistor and a forming method for a storage. The invention avoids the residue problem caused by unclean removing the second polysilicon layer by removing the first polysilicon layer formed on the semi-conductor substrate and the second polysilicon layer on the inter-level dielectrics layer first, and then defining to carve the first polysilicon layer and the inter-level dielectrics layer to form the grid, thus preventing the leakage current generated by the high-voltage transistor due to the residue problem of the second polysilicon layer.