Theoretical analysis and experimental study on noise characteristics in cross gain modulation (XGM) wavelength conversion based on the copropagating and the counterpropagating configuration are presented. Results show that amplified spontaneous emission noise in counterpropagating configuration is more serious than that in copropagating configuration. Carrier consumption induced by amplified spontaneous emission, gain dispersion and internal loss in active region are all taken into account in numerical calculation which is based on section amplifier model and transfer matrix method. It can be shown from theoretical calculation that the amplified spontaneous emission noise power is mainly related to the carrier density while the power difference between two operational configurations is mainly determined by the uniform spatial distribution of the carrier density.