The thesis developed a set of Photovoltaic solar power grid data acquisition system which includes functions of data acquisition,analysis&process and measurement correction.In order to solve the measurement error caused by zero drift and nonlinear characteristics of components, thesis proposed a kind of data calibration algorithm based on sector least square method.It set up the standard values of photovoltaic date acquisition system by measurement standard table, do measurement calibration for system by Piecewise least squares fitting method, and decide whether system meets design requirements by comparing Standard to measure value and calibration value. The experimental results indicate that Piecewise least squares fitting method can compensate the measurement error of the system effectively, The measurement error has been reduced 89.6% after using Gridconnected PV data acquisition system and calibration algorithm compared with metrical date without calibration, measurement accuracy been improved effectively.