The hole of the locking hole steel plate is square and can be locked to other structures by bolts for fixed connection. The hole of the splayed steel plate is splayed, which can be connected with other structures by bolts to play a supporting and bearing role. Keyhole steel plate is suitable for the occasions where fixed connection is needed in construction, bridges and other engineering projects. Eight-hole steel plate is suitable for shelves, supporting structures and other occasions that need support and bearing.