Fitness testing and evaluation on policy and activity development played important role. The most of the instruments price was too high to popularize at present. The purpose of this study was focused on fitness testing of sit-up, a simple design and a fair price instrument. It mainly combined logic electric cable with an inducted machine that matched with an organization of machinery for sit-up testing and passed through the indication that could know the score. The whole process was accomplished by logic electric cable and an inducted machine instead of testing by person that could save human power, avoid mistake, also enhanced accuracy.