Abstract: The handy intelligent pulling force instrument was designed for measuring pulling forces of agricultural machinery. By using modern element and advanced software technology, automatic error correction of zero point and data filtering, and high measuring accuracy were realized on the instrument. Because the circuit applied common voltage, the error resulted from the increasing and decreasing of the voltage was eliminated. Less power and little temperature effect were made due to wide use of CMOS IC. The instrument has passed the test and achieved or exceeded the standard of the same trade. Good results were achieved through consumer's application for one year.