UBV observations of the peculiar variable star CH Cygni from 1968 up to 1974 are presented. HD 182691 served as a comparison star. It turned out that the colours are in accordance with a model for a symbiotic star. The colour-magnitude diagrams of CH Cygni allow dividing the period of the observations into two parts in dependence on the activity of CH Cygni. Observed brightness variations are analyzed by using autocorrelation, crosscorrelation, and power spectral density functions. It has been found that brightness variations have some periods which are given.