Controlling the spin transport in solids electrically is central to the application of spintronics for the development of information technology.Since the spin-transistor was proposed by Datta and Das in 1990s,due to the difficulties of spin injection and detection in semiconductors,until now there is still no efficient spin field effect transistor developed.Here we report the tunability of the planar Hall resistance in ferromagnetic half metal Co2FeAl devices solely by piezo voltages without external magnetic field at room temperature,which can be analogously used as the n-type and p-type field effect transistor,respectively.