Abstract: The field spectral data collection of trees for remote sensing application has been carried out for about two years.Several variables encountered in situ for spectral measurement should be calibrated or kept in mind.The hemispherical reflection properties of several tree species were investigated. The reflex reflection performance of tree canopy as well as spectral and goniometric properties of reference panel serve as a basis for analysis of uncertainties introduced by differing illumination conditions.Large field of view (FOV)is suggested for forest canopy spectral measurement to avoid sharp radiance variations due to different FOV contents.Multiband radiometer seems more suitable to large scale data collection project in forestry than delicate spectrometers,provided the band selection of the sensor has been decided.