This paper is devoted to analyse the three-qubit Heisenberg XX rings in a uniform magnetic field

and by controlling of the coupling of a site we can change the entanglement between other two sites.We find that thermal entanglement exhibits a platform-like behaviour and entangled value is equal to 1 when coupling of the site which was controlled is small than that was not controlled

the width of the platform-like region could be controlled by changing the coupling between was not sites

This novel property may be used as a quantum entanglement switch.At the same time

we analyse the situation that two sites were controlled

the entanglement maximal switch still can be realized.Moreover

we find that there are linear relation in the spin-spin interactions.