Unusually large and compressively strained Si in nanoheterostructures of Ni silicide/Si/Ni silicide, in which the strain of the Si region can be achieved up to 10%, has been produced with point contact reactions between Si and Ni nanowires in an ultrahigh vacuum transmission electron microscope. The growth rate and relationships between the strain and the spacing of the Si region have been measured. Based on the rate and relationships, we can control the Si dimension and, in turn, the strain of remaining Si can be tuned with appropriate spacing. Since one-dimensional nanoheterostructures may have potential applications in nanoelectronic devices, the existent strain will further affect carrier mobility and piezoresistance coefficients in the Si region. Electrical measurements on the nanodevices from such nanoheterostructures show that the current output closely correlates with the Si channel length and compressive strain.