Data acquisition system requires high accuracy. When the data acquisition system designed with 12-byte high resolution AD774BKN and directly used the nominal value components, it still existed system error. The traditional linear parameters scale transform method can eliminate system error, but it happens when the data acquisition is linear system. If there is a saturation of nonlinearity, it is better to measure several data in a variety of input cases and make segment handling. Using the traditional scale transformation to deal with the saturation data and using the linear relationship by the least squares fitting scale transform with non-saturation can get the measured values. The experimental results show that calculation measurements using this method are much better accurate than the traditional scale transformation. It can get good effect to improve the system accuracy.