High-precision ADC linearity test method and system

The invention discloses a high-precision ADC linearity test method and system, and the method comprises the steps: inputting a plurality of signal differences to an ADC through the channels of a control signal generator, a voltage source, an arithmetic unit and a multiplexer, and obtaining a group of output code bits of each signal difference; summing and subtracting the two preset signal differences, and summing and subtracting the output code bits of the two preset signal differences to obtain summing and subtracting results; determining a multivariate linear equation set according to a preset piecewise nonlinear model containing to-be-solved parameters, summation and subtraction results and an output code bit; and solving the equation set to obtain an optimal solution, and determining an integral nonlinear error and a differential nonlinear error of the ADC according to the optimal solution and a preset piecewise nonlinear model. According to the invention, a common mode part and a differential mode part o