Abstract: A lateral force microscope (LFM) was used to investigate nanoscale friction behavior of GeSbTe films of 50 nm thickness prepared by magnetron sputtering. Effect of relative humidity, scanning rate, surface roughness on friction and adhesive force was taken into account. Besides, friction behavior of GeSbTe films with different composition was analyzed. Moreover, the morphologies of GeSbTe films were observed on the atomic force microscope (AFM), and their hardness and elastic modulus values were also measured with a nanoindenter. It was found that scanning rate had some effect on the friction between tip and GeSbTe films under high humidity. The average friction values under the same applied load were nearly linear to surface roughness when the external applied load is higher. However, the two variables presented non-linear relationship when the applied load was lower. Effect of humidity on adhesion between the tip and GeSb_2Te_4 film was more significant than that between tip and Ge_2Sb_2Te_5 film, and adhesion reduced the friction coefficient; Under the same humidity, difference of film's hardness which arise from the variation of film's composition had a certain effect on the film's friction performance. It is suggested that the anti-compression ability of GeSbTe films should be enhanced besides adding protective coating if the phase mechanism is not affected.