A method for jointly calibrating external parameters of multiple cameras, the method comprising: determining an overlapped area of angles of view of cameras, and obtaining a two-dimensional, 2D, verification point set in an image of the overlapped area, the 2D verification point set comprising at least one verification point; performing external parameter calibration for each camera separately to obtain a current external parameter of each camera; calculating coordinates of a three-dimensional, 3D, point corresponding to each verification point in a world coordinate system using the current external parameter of each camera separately and a combination of a ground equation and an internal parameter of the camera, and calculating a loss function based on the coordinates of the 3D point corresponding to each camera, the loss function being used to measure an overlay error of calibration of the cameras under the current external parameter; and performing joint calibration based on the loss function to obtain a target external parameter of each camera, wherein calculating the loss function based on the coordinates of the 3D point, comprises: using any verification point as a current verification point, and calculating a variance based on coordinates of a 3D point of the current verification point obtained by calculation corresponding to each camera; and summing variances obtained by calculation corresponding to verification points, and using a sum value as the loss function, wherein calculating the loss function based on the coordinates of the 3D point, further comprises: determining a minimum distance value between any two 3D points in 3D points of the current verification point obtained by calculation corresponding to each camera; and adding to the loss function obtained by calculation the minimum distance value corresponding to each verification point obtained by calculation to obtain a final loss function. determining an overlapped area of angles of view of cameras, and obtaining a two-dimensional, 2D, verification point set in an image of the overlapped area, the 2D verification point set comprising at least one verification point; performing external parameter calibration for each camera separately to obtain a current external parameter of each camera; calculating coordinates of a three-dimensional, 3D, point corresponding to each verification point in a world coordinate system using the current external parameter of each camera separately and a combination of a ground equation and an internal parameter of the camera, and calculating a loss function based on the coordinates of the 3D point corresponding to each camera, the loss function being used to measure an overlay error of calibration of the cameras under the current external parameter; and performing joint calibration based on the loss function to obtain a target external parameter of each camera, wherein calculating the loss function based on the coordinates of the 3D point, comprises: using any verification point as a current verification point, and calculating a variance based on coordinates of a 3D point of the current verification point obtained by calculation corresponding to each camera; and summing variances obtained by calculation corresponding to verification points, and using a sum value as the loss function, wherein calculating the loss function based on the coordinates of the 3D point, further comprises: determining a minimum distance value between any two 3D points in 3D points of the current verification point obtained by calculation corresponding to each camera; and adding to the loss function obtained by calculation the minimum distance value corresponding to each verification point obtained by calculation to obtain a final loss function. using any verification point as a current verification point, and calculating a variance based on coordinates of a 3D point of the current verification point obtained by calculation corresponding to each camera; and summing variances obtained by calculation corresponding to verification points, and using a sum value as the loss function, wherein calculating the loss function based on the coordinates of the 3D point, further comprises: determining a minimum distance value between any two 3D points in 3D points of the current verification point obtained by calculation corresponding to each camera; and adding to the loss function obtained by calculation the minimum distance value corresponding to each verification point obtained by calculation to obtain a final loss function. determining a minimum distance value between any two 3D points in 3D points of the current verification point obtained by calculation corresponding to each camera; and adding to the loss function obtained by calculation the minimum distance value corresponding to each verification point obtained by calculation to obtain a final loss function.