High precision OCXO based on SC cut overtone crystals can show very high frequency stability and aging. However, its frequency regulation range by voltage control is not wide. When high precision OCXO is used as the standard of precise controllable measuring instruments, especially the precision slave VCOCXO, in allusion to widen frequency comparison range, the precision OCXO should not only show nice frequency stability and aging, but also can be regulated and controlled in a relative wide frequency range. Using a fundamental crystal it is impossible to obtain this result. In allusion to wider frequency regulation range, we propose a new method through regulating the control temperature of the OCXO. With this way all the good performances of precision OCXO are kept, and, at the same time the original 10−7 order voltage-controllable frequency range is improved into 5×10−6 or wider.