Abstract: The indicator of the traditional demonstration experiment of the ＂overweight＂, ＂weightlessness＂ is difficult for the student to see clearly and read it. And it is disadvantageously to the students to understand overweight and weightlessness. In improvement experiment, the indicator is static in overweight （or weightlesshess） position. The students can accurately read out the number of degree, as soon as they compare it with the ob）ect actual gravity. So they can obtain the concept of ＂overweight＂ or ＂weightlessness＂.

Key words: spring balance, overweight, weightlessness, demonstration experiment, improvement, guide rail, dialing piece