Abstract: Time changes in transfer functions of short period geomagnetic variations in 28 years from 1960 through 1987 are studied, systematically and in detail in this paper. The results indicate that : (1) It is evident that seasonal and secular changes in the transfer functions A at exists the Guangzhou geomagenetic observatory. The character for seasonal change are large in summer and smaller in winter with main cycles of 12 months and 6 months. The character for secular change is a descend with a rate of 0.0025 per year. The seasonal and secular changes in transfer functions B are not evident. (2)The direction of Parkinson vector at Guangzhou geomagnetic observatory is clearly affected by the ocean, and is associated with coastal effect. (3)The values of transfer functions A and B are related to geomagnetic activity at = 0.05. Secular change is not related to geomagnetic activity, maybe it is affected in a great measure by earth conductivity change.