Abstract: In order to accurately adjust the brightness of the overlapping area of multi-channel projection images, a projection image edge fusion method based on B-spline curve was designed. Firstly, the parameters of attenuation function and gamma correction were set according to the projection screen, external light environment and the nature of the projector itself. Then, the overlap area of the projection image was acquired by the camera and the color intensity of each pixel was calculated, and the peak signal-to-noise ratio was calculated by the ideal value. Then, the correction accuracy and flexibility of quadratic B-spline curve and cubic B-spline curve were compared. Finally, the edge brightness of the projection image was optimized by cubic B-spline until the peak signal-to-noise ratio reached the standard value. The experimental results show that the peak signal-to-noise ratio of the channel R in the overlapped area of the projection image is increased by 9.13 dB, that of the channel G by 6.09 dB, and that of the channel B by 7.53 dB. The edge brightness optimization technology of projection image based on B-spline curve improves the accuracy of brightness adjustment in overlapping area of projection image.