A fixing structure used for quickly assembling on boundary card is prepared as using an elastic body as main body and setting fixture body at one end of main body, enabling to set fixture body above afixing hole of host board set with a insertion slot of small peripheral element connection boundary, setting positioning element at internal side of main body and positioning said positioning elementon boundary card to make boundary card be positioned on host board firmly after boundary card of small peripheral element connection boundary is inserted in insertion slot of small peripheral elementconnection boundary.