Due to its shape memory effect and superelastieity, shape memory alloy is one of the attractive smart materials which has been paid attention on for decades.Especially in Ni based, Cu based, CoNi based and NiTi based alloys.But further system should also be explored.In this work martensitic transformation was firstly confirmed in the off-stoichiometric Co-V-Si Heusler alloy, in which the martensite has an ordered D022 tetragonal structure transformed from L21 parent phase (Fig.1).The results also show that reverse martensitic transformation temperatures of Co63.5V17.0Si19.5 alloy are about 743 ℃ (Fig.2).Furthermore, a 3.1％ of recovery strain can be obtained at high temperature in Co63.5V17.0Si1g.5 alloy, which both make this alloy potential for the application of high-temperature shape memory alloys.Otherwise, due to the high transformation temperature and the phase relationship.The parent phase transforms to the other phase (A12) as soon as the reverse martensitic transformation happens.So the thermal stability of martensite in the Co-V-Si alloy is also proved to be insufficient.