When a guyed tower is designed it is designed as a unit which includes the guy wires and the tension in them. It is important that the tension in the wires be kept close to the design value, since a tension greater or lower than designed could allow the tower to bend and perhaps fail under high winds. The uneven tension in the guy wires could distort the tower and make it susceptible to wind damage. Excessive tension may cause alignment problems and even a cable rupture. It may cause permanent wrapping of tower structural parts. And too large preload will reduce the ability to absorb additional load (from the tower moving) before the guy reaches its breaking strength. This report describes in detail, the some methods for measuring initial tensions in guys of guyed tower have been applied in Vietnam.