The invention discloses a method and system for calibrating a camera based on a 2D planar template. The method includes the following steps: acquiring a calibration image of a checkerboard, wherein the calibration image includes a plurality of angular points; removing the angular points from the plurality of angular points that have a first error value greater than a first preset value by adoptingthe random sample consensus algorithm, obtaining target angular points; based on the coordinates of the target angular points and the corresponding world coordinates, acquiring homograph matrices; removing the homograph matrices that have a second error value greater than a second preset value by adopting the random sample consensus algorithm, acquiring target homograph matrices; based on the target homograph matrices, acquiring a target second curve model, and based on target second curve model, acquiring the initial parameters of a camera; and estimating the initial parameters by using themaximum likelihood estimation method, acquiring target parameters, and calibrating the camera by using the target parameters. According to the invention, the method overcomes low accuracy in calibrating cameras of the Zheng Zhengyou calibration method.