Provided are a method and an apparatus for correcting a color convergence error, and a device. The method includes: in a darkroom environment, acquiring a projection image obtained by projecting a test pattern containing N white shape points by a projection system, where N is an integer greater than or equal to 2; performing color separation on N shape image points on the projection image, to obtain N shape image points corresponding to R, G, and B color components respectively; determining color coordinates corresponding to R, G, and B according to the N shape image points corresponding to R, G, and B color components respectively; and adjusting an assembly parameter of the projection system according to the color coordinates corresponding to the R, G, and B. The present disclosure may detect and correct color convergence error of the projection system.